Download Table of content

Table of content
Abstract
1. Introduction ............................................................................................................................................. 1
1.1. Research Question......................................................................................................................................... 2
1.2. Clarification of keywords in the research question .......................................................................... 2
1.3. Delimitation of the assignment ................................................................................................................ 2
1.4. Structure of the assignment ....................................................................................................................... 3
1.5. Work method .................................................................................................................................................. 3
1.5.1. Inclusion & exclusion criteria ............................................................................................................................. 6
1.5.2. Selection of papers .................................................................................................................................................. 6
2. Meta-theory plan .................................................................................................................................... 7
3. Theory ........................................................................................................................................................ 8
3.1. Energy intake .................................................................................................................................................. 8
3.2. Macronutrients ............................................................................................................................................... 9
3.2.1. Dietary fat ................................................................................................................................................................... 9
3.2.1.a. Digestion & absorption .................................................................................................................................................... 10
3.2.2. Dietary protein ...................................................................................................................................................... 10
3.2.2.a. Digestion & absorption .................................................................................................................................................... 11
3.2.3. Dietary carbohydrate .......................................................................................................................................... 11
3.2.3.a. Digestion & absorption .................................................................................................................................................... 11
3.2.4. Dietary fiber ............................................................................................................................................................ 12
3.2.4.a. Digestion................................................................................................................................................................................. 12
3.3. Gastric emptying .......................................................................................................................................... 13
3.4. Thermic effect of food ................................................................................................................................ 14
3.5. Satiety .............................................................................................................................................................. 14
3.5.1. The biological process of satiety .................................................................................................................... 15
3.6. Scales ................................................................................................................................................................ 16
3.6.1. Visual analogue scales ........................................................................................................................................ 16
3.6.2. Seven-point bipolar equilateral rating scales ........................................................................................... 17
4. Results ..................................................................................................................................................... 17
4.1 Methodology ................................................................................................................................................... 18
4.1.1. Study design and procedure ............................................................................................................................ 18
4.2. Matrix ............................................................................................................................................................... 19
4.3. Satiety .............................................................................................................................................................. 24
4.3.1. Hunger ....................................................................................................................................................................... 24
4.3.2. Fullness ..................................................................................................................................................................... 25
4.3.3. Subsequent Meal Intake ..................................................................................................................................... 25
4.4. Other parameters ........................................................................................................................................ 26
4.4.1. Desire to eat ............................................................................................................................................................ 26
4.4.2. Pleasantness ........................................................................................................................................................... 27
4.4.3. Prospective consumption .................................................................................................................................. 27
4.4.4. Gastric emptying ................................................................................................................................................... 27
5. Discussion .............................................................................................................................................. 27
5.1 Literature considerations .......................................................................................................................... 41
6. Conclusion ............................................................................................................................................. 44
7. Perspectives .......................................................................................................................................... 44
8. Practice considerations .................................................................................................................... 45
9. List of reference ................................................................................................................................... 47
Abstract
Title: Dietary macronutrients as determinants of short-term satiety in adults: a literature review
Authors: Marianne Hansen and Sammy Elshikh
Background: The prevalence of overweight and obesity has lead to an increased number of noncommunicable diseases; this has sharpened the focus on developing useable tools for weight
control.
Objective: This thesis aims to provide a review investigating dietary macronutrients effect upon
satiety and whether or not it may influence subsequent meal intake.
Method: The systematic literature search included 1586 titles. The studies concerned healthy adults
and Caucasian subjects. From the 1586 titles, 10 papers where deemed as qualified and included.
Results/Conclusion: There was suggestive evidence for protein contributing to a superior effect on
satiety compared to the other macronutrients. In addition fat seemed to be the least satiating
macronutrient, risking overconsumption of food. The satiating effect of macronutrients does,
however seem to be limited to a short time period (3-4 hours). Furthermore it must be investigated
whether or not the quantity, meal type, food structure etc. may be of superior influence in regards to
satiety. Moreover the thesis has examined how the results may be used for clinical practice, within
the profession of health.
1. Introduction
Overweight and obesity is becoming an increasing health problem and is affecting a vast number of
people around the world. Nearly half of the world's population have become overweight: "In 2014,
39% of adults aged 18 years and older (38% of men and 40% of women) were overweight" (WHO,
2014, p. 79). Furthermore the WHO has classified half a billion people as obese. Due to overweight
and obesity, non-communicable and lifestyle diseases has been on the rise causing an estimated 3.4
million deaths per year (WHO, 2014, p. xiv). The reasons for the increased incidence of obesity and
overweight have been investigated by numerous health professionals and the results tend to lean
toward lifestyle-habits and environmental factors as being the primary cause (Aljuraiban et al.,
2015). Research shows that the modern diet has an increased share of fast-foods, which is caloric
dense and contains few fibers, fruits, vegetables and has an overall lack of wholesome and healthy
food sources (Byrd-Bredbenner, Moe, Beshgetoor, & Berning, 2012, p. 72). This change in
nutrition and food sources seems to have caused the increased prevalence in overweight, creating
stress on our healthcare system, due to the difficult treatment of obesity. Current methods for
effective treatment of obesity, relies on either surgery or low calorie diets (Byrd-Bredbenner et al.,
2012, pp. 342–343). By learning and understanding how we most effectively can control weight, we
might be able to create safer and better alternatives to the current treatments.
The effect of the diet's macronutrient composition on weight maintenance has been
investigated as an alternative for effective weight control, within the adult population. However no
conclusive evidence for living on a macronutrient specific diet was found, when considering weight
maintenance (Fogelholm, Anderssen, Gunnarsdottir, & Lahti-Koski, 2012). The systematic
literature review by Fogelholm et al. (2012) showed strong indications for evidence on energy
balance and caloric intake being the primary role in weight change and that the macronutrient
composition of the diet was ineffective in predicting weight gain. The review by Fogelholm et al.
(2012) did point toward other mechanisms that might be relevant in regards to weight control, for
example adherence to the specific diet. In studies investigating the macronutrient composition the
majority of the diet trails had a relative high dropout rate, which could indicate that some diets are
more demanding to follow than others. The results of the studies by Layman et al. (2009), Larsen et
al. (2010) and Aller et al. (2014) showed a tendency toward a high protein diet resulting in better
adherence. This could mean that even though a specific macronutrient distribution might not be
effective in regards to short-term weight control, it might still be favorable for long-term adherence.
1
As adherence to the diet is of uttermost importance, when favoring long-term weight control, this
would be relevant to investigate.
In certain cases adherence may be related to satiety; the less hunger you feel, the
easier it is to stay on track (Byrd-Bredbenner et al., 2012, pp. 332–333). The aim of this thesis is to
investigate the satiety rating of the different macronutrients and how they may affect the satiety
response in adults. We will hereby examine whether or not a specific macronutrient composition
may be correlated to better satiety, thereby becoming a valuable tool when designing adherable
weight loss strategies.
1.1. Research Question
How does the different macronutrients affect the short-term satiety in healthy adults?
1.2. Clarification of keywords in the research question
Macronutrients are categorized into protein, fat, carbohydrate and fiber. Normally fiber is not
defined as an individual macronutrient, but is simply separated in this thesis due to its difference in
calorie content and digestive process. All the macronutrients are viewed as dietary, meaning they
are obtained and present in food.
Short-term is defined as ≤24 hours.
Satiety is defined according to Gerstein, Woodward-Lopez, Evans, Kelsey, & Drewnowski (2004),
as the fullness experienced intra- and inter-meal.
Healthy is defined as people without any non-communicable diseases and a BMI ≤30 kg/m2.
Adults are defined as people ≥18 years of age.
1.3. Delimitation of the assignment
Delimitation was carried out in order to make a clear focus for the thesis and provide a qualitative
discussion. This thesis is limited to cover “the macronutrients short-term effect on satiety”;
2
relevant themes, such as the diet's effect on health will therefore not be included due to limited
space/characters. We have also chosen to withdraw the link between satiety and hormonal
responses, in the results, as it is a complex subject, which would require a study for itself.
Furthermore other components such as blood parameters will not be included within this thesis.
Neither will we be evaluating the macronutrients within their own subgroups; for example saturated
and unsaturated fatty acids, this is also the case for alcohol, which will not be reflected upon, due to
limited space. Moreover this thesis will only include human studies, as animal studies measuring
satiety may not be directly related to humans, due to the clear physiological differences and means
of measurements. In addition children and adolescents below the age of 18 are disqualified from
this thesis. Furthermore, people with non-communicable diseases, obesity and smokers are
excluded from the included literature, given the fact that it influences several physiological
processes (Gregersen et al., 2011). In order to make sure all relevant studies was included in the
search; the literature search did not have any restrictions on study types. However this thesis only
includes Randomized clinical trials, due to the high ranking in the hierarchy of research evidence
(Kjøller, Juel, & Kamper-Jørgen, 2007, p. 371). Studies designs with within-subject,
counterbalanced or crossover design were included in the thesis.
1.4. Structure of the assignment
You will be able to view our work method and how the included literature was discovered. In order
to have a comprehensible understanding of our theme, a section with relevant theory is included.
Here you will be able to read about our meta-theory, macronutrients, biological processes and
satiety. The results, from the included literature, will be presented in a matrix in order to make it
easy to access and examine, in addition the results will be summarized. Moreover the results will be
discussed in the following section. This will be the primary part of this thesis, where the content
will reflect upon the research question. The thesis will lastly be summed up in the conclusion,
thereby providing a concrete answer to our research question. Further perspectives and the
professional practice considerations can be viewed at the end of the thesis.
1.5. Work method
The work method will be constructed to discover studies regarding satiety and how it is affected by
different macronutrients, providing knowledge to weight control and treatment of overweight and
3
obesity. The literature search was conducted in the PubMed and Embase databases. These databases
are used, as PubMed is a medical database consisting of a variety of articles within health. A search
in Embase was done afterwards in order to secure that relevant European literature also was
included. Lastly the literature lists of the studies were looked through, to ensure that we included
other significant and relevant studies in the thesis.
The search terms used in PubMed are shown in table 1. MeSH terms are used for all
the macronutrients in theme 1, in order to narrow down the search to relevant articles concerning
dietary macronutrients. In theme 2 the MeSH term ‘satiation’ is used in order to retrieve as many
relevant articles as possible. PubMed defines satiation as “Full gratification of a need or desire
followed by a state of relative insensitivity to that particular need or desire.” (NCBI, n.d.-b).
Furthermore a subgroup for satiation is ‘satiety response’; thereby the search also included articles
concerning satiety. Lastly ‘satiety’ was used, as an all field term, to make sure articles without the
MeSH term tags ‘satiation’ and ‘satiety response’ also were included. In theme 3 the MeSH term
‘hunger/physiology’ is used, because only articles including the physiological aspect of hunger is
relevant for the thesis. Furthermore hunger has its own theme, as we are not interested in articles,
which does not include both satiety and hunger. The MeSH term Adult is not included in the
PubMed Search, because it is defined as the age of ≥19 (NCBI, n.d.-a).
The search terms used in Embase are shown in table 2. In theme 1 the search of
dietary macronutrients is made with a broad search, this is done as Embase do not have any Emtrees
for the dietary macronutrients. A broad search was chosen instead, because it includes both the
words as Emtree and without, e.g. the search term dietary fiber includes: (Dietary AND (Fiber/exp
OR fiber)). Hereby it makes sure that we include as many relevant articles as possible in our search.
Theme 2, satiation is a broad search, due to the same reasons as in theme 1. Furthermore satiety is
included as an Emtree in order to retrieve more relevant articles. In theme 3, hunger is a broad
search and not an Emtree, due to the fact that the Emtrees branches for hunger did not cover the
areas we were interested in. Lastly theme 4 includes adults as delimitation, since this Emtree is
defined as the age of ≥18.
4
Table 1 - Search terms PubMed
Theme 1
AND
Theme 2
Dietary Proteins
(MeSH)
Satiation
(MeSH)
OR
OR
Dietary Fats (MeSH)
Satiety
(All Fields)
AND
Theme 3
Hunger/physiology
(MeSH)
OR
Dietary Fiber (MeSH)
OR
Dietary
Carbohydrates
(MeSH)
Tabel 2 - Search terms Embase
Theme 1
AND
Theme 2
Dietary fiber
(Broad search)
Satiation
(Broad search)
OR
OR
Dietary
carbohydrate
(Broad search)
Satiety (Emtree)
AND
Theme 3
Hunger
(Broad search)
AND
Theme 4
Adult
(Lim)
OR
Dietary
protein
(Broad search)
OR
Dietary fat
(Broad search)
5
1.5.1. Inclusion & exclusion criteria
The inclusion and exclusion criteria of the literature was as following:
Participants:
Diet:

Age ≥18

Fixed test meals (kcal or mass)

Healthy

Preloads allowed

Caucasian

Diets regarding
Exclusion:

Non-communicable diseases

Smokers

Obese (BMI ≥30)

Eating disorders
Study type:
o
Dietary fat
o
Dietary protein
o
Dietary Carbohydrate
o
Dietary fiber
Exclusion:

Weight Loss programs

Sensory-specific satiety
Protocol

Randomized Control Trial

Fast ≥8 or overnight

Crossover design

Short-term (≤24 hours per session)

Within-subject design

Counterbalanced
1.5.2. Selection of papers
The search terms, for the selection of papers, resulted in 1286 hits, where an additional 300 titles
were added from reference lists. The study titles were deemed relevant or unqualified, which
resulted in 82 relevant abstracts. The abstracts were read closely and those who did not meet the
inclusion criteria were excluded, resulting in a total of 36 papers for skim reading. 18 papers were
deemed qualified and were thoroughly read. Eight papers were excluded for not fulfilling the
inclusion criteria, leaving 10 papers for this thesis. The exclusion process is shown in figure 1.
6
Figure 1 - Flow-chart of the exclusion process
PubMed
Embase
References
Titles
(n = 972)
Titles
(n = 314)
Titles
(n = 300 )
Total titles screened
(n = 1586)
1504 excluded as not
being qualified
82 abstracts
46 papers excluded
as not being qualified
36 skim-read papers
18 papers excluded
as not being qualified
18 full papers
8 papers excluded as
not being qualified
10 papers included
2. Meta-theory plan
The method that forms this thesis is stated as a literature review and is considered for providing a
strong scientific basis in the hierarchy of evidence, which makes it applicable for practical and
clinical recommendations (Evans, 2003). The meta-theory and philosophy of science, which
constitutes the primary work of this method, is positivism. Positivism is based on the classical
empiricism and is described as science being derived through gathering of empirical and
7
observational data. This leads to the concept of cumulative science; within this notion, science is in
constant development through the accumulation of knowledge, which is gathered from observations
and experiments (Holm, 2013, p. 30). Cumulative science is the very foundation of a literature
review, as new knowledge is constantly gathered through new studies/experiments and continues
building on the current literature of evidence. Through literature reviews, which examine the
current available information, we are able to observe the data and interpret it through reason and
logic. This makes us able to put forward theories that may be verified; because only verifiable
theories are scientific and can become valid knowledge (Holm, 2013, p. 31). With this approach
observations and logic are interconnected, this perspective is the very groundwork of the provided
science and an example of how rationalism can be incorporated to structure the observed data, in
order to make data processing possible, which is essential for evidence based recommendations
(Hjørland, 2011).
3. Theory
When investigating satiety, it is necessary to include some background of the factors and theory that
are related to the subject. Satiety is a complex matter as there are many aspects to examine, both in
regards to physiological functions such as hormones (Byrd-Bredbenner et al., 2012, p. 321), as well
as psychological features such as perception and subjective ratings (Gregersen et al., 2011). By
exploring current research and evidence related to macronutrients and their satiating effect, we will
be including the linked factors that may have an important part in the functions of satiety.
3.1. Energy intake
The body can obtain energy from four different nutrient sources: carbohydrates, fats, protein and
alcohol. These macronutrients are able to participate in bodily functions, such as building new
components and aid in muscular movements (Byrd-Bredbenner et al., 2012, p. 10). The energy
provided by the macronutrients is commonly termed as kilocalories (kcal), which will also be the
general term used throughout this thesis. The energy contained in a specific food can be measured
through practical tools or simply by adding the fuel values from the grams of carbohydrate, fat,
protein and alcohol (Geissler & Powers, 2005, pp. 27–28).
8

Fat 9 kcal/g
(Ibid)

Protein 4 kcal/g
(Ibid)

Carbohydrate 4 kcal/g
(Ibid)

Fiber 2 kcal/g
(Byrd-Bredbenner et al., 2012, p. 157)

Alcohol 7 kcal/g
(Geissler & Powers, 2005, pp. 27–28)
When considering energy intake and calories in relation to satiety, we must also consider energy
density as a factor. Energy density is determined by measuring the foods calorie content and
comparing it with the given weight of a food. As fat has the highest calorie content per gram, it is
often present in high energy-dense foods, such as fatty meats, crèmes and fried foods. These foods
weigh relatively little compared to their calorie content. On the other hand food sources containing
low fat, high fiber and high protein are often relatively low in energy density, because of a higher
water content, which increases weight, but has no effect on calorie content, due to water being
calorie free. Examples of low energy density foods are fruits, greens and low fat meats. As these
low energy dense foods can produce greater volume, relative to their calorie amount, they may
achieve greater satiety compared to their counterpart, when accounting for energy intake (ByrdBredbenner et al., 2012, p. 52).
3.2. Macronutrients
To achieve a greater understanding on the possible satiating effect of the different macronutrients,
they will be described through their digestion and absorption.
3.2.1. Dietary fat
Fats, also known as lipids, have several features: for example its creamy texture and its ability to
add taste to foods, which makes it a popular part of our daily diet. It is present in the majority of the
modern society's food choices and it is found in everything from vegetable to animal products.
Other than providing food features that can increase the sensation of taste, it also adds important
vitamins. Fats have many roles in our body and are essential for different mechanisms to function
(Geissler & Powers, 2005, p. 97). It is also the most caloric dense energy source that we can absorb
(Geissler & Powers, 2005, pp. 27–28).
9
3.2.1.a. Digestion & absorption
The digestion of fat begins when the food enters our mouth; here the enzyme lingual lipase is
secreted to begin the digestion of the triglycerides, containing short and medium chain fatty acids.
When the fat reaches the stomach, gastric lipase breaks triglycerides into diglycerides,
monoglycerides and free fatty acids. However due to fats insolubility, a limited amount is digested
in the mouth or stomach. (Geissler & Powers, 2005, pp. 106–107). As the fat moves to the small
intestine, the hormone cholecystokinin (CCK) is released from the intestinal cells; this will
stimulate the gallbladder to release bile and the pancreas to release lipase and colipase. Bile will
then emulsify the fat into small fat droplets, known as micelles, this increases the surface area of the
fat. With a larger surface area lipase is able to break down the triglycerides into monoglycerides and
free fatty acids; this process is supported by the colipase, which helps the lipase attach to the
droplets (Ibid). Phospholipids and cholesterol is also digested in the small intestine: With help of
enzymes from the pancreas and the small intestine, phospholipids and cholesterol are broken down
to glycerol, fatty acids and other components (Ibid).
After the digestion, the fat is absorbed by the brush border of the absorptive cells, in the duodenum
and jejunum within the small intestine. Depending on the carbon chain length of the fatty acids and
monoglycerides, they will be absorbed by either the lymphatic or the cardiovascular system (ByrdBredbenner et al., 2012, pp. 204–205). After absorption they are reformed into triglycerides; the
short and medium chained fatty acids will enter the bloodstream via the cardiovascular system. The
long chained fatty acids will enter the lymphatic circulation together with cholesterol and vitamins.
Approximately 95% of dietary fat is absorbed; the last 5% is excreted through the large intestine
(Ibid). The fat is then transported as different lipoproteins, which enables them to circulate in the
blood (Byrd-Bredbenner et al., 2012, p. 206).
3.2.2. Dietary protein
Proteins are an essential structure of our body and are found in all of our cells and components:
muscle, organs, DNA, blood, enzymes and many others are build on protein, it is therefore an
important component within many functions (Byrd-Bredbenner et al., 2012, pp. 339–343).
10
3.2.2.a. Digestion & absorption
The digestion of proteins begins in the stomach, where hydrochloric acid is secreted; this acid helps
to denature the proteins. The hormone gastrin releases the enzyme pepsin in the stomach, which
will begin to break the long polypeptide chains, into shorter amino acid chains through hydrolysis.
The partially digested protein then moves to the small intestine. In the small intestine the hormones
secretin and CCK is released, these will stimulate the pancreas to release the enzymes trypsin,
chymotrypsin and carboxypeptidase. These enzymes will finally break the polypeptides into short
peptides and amino acids, which will be absorbed in the small intestine (Geissler & Powers, 2005,
p. 80). The absorbed amino acids will be transported to the liver through the portal vein, here they
will be used for protein synthesis, energy, or partake in other functions (Byrd-Bredbenner et al.,
2012, p. 238).
3.2.3. Dietary carbohydrate
Carbohydrates are important for our cells as they provide an easily available energy source and can
be used by our muscles and even our nervous system. Carbohydrates can, in small amounts, be
stored in blood, muscle and liver, which help to provide a stable blood glucose level and readily
available energy (Byrd-Bredbenner et al., 2012, pp. 168–170).
3.2.3.a. Digestion & absorption
The carbohydrates are digested in different stages, depending on the structure and whether it is a
simple or complex carbohydrate (Byrd-Bredbenner et al., 2012, p. 170). The first digestion process
begins in the mouth, where the enzyme salivary amylase breaks down amylose into smaller
polysaccharides and disaccharides (Astrup, Bügel, dyerberg, & Sten, 2015, p. 126). When the food
reaches the stomach, the salivary amylase is inactivated, by the stomach acidity and no further
digestion occurs until the food passes into the small intestine. The pancreas secretes the enzymes
pancreatic amylase and dextrinase into the duodenum and the digestion of the amylose continues.
Dextrinase also begins the breakdown of amylopectin (Byrd-Bredbenner et al., 2012, pp. 170–171).
When the polysaccharides are broken down to disaccharides three enzymes in the wall of the small
intestine continuous the digestion. The three enzymes in the small intestine are: (1) lactase, which
break down lactose into glucose and galactose, (2) sucrase, which digest sucrose into glucose and
fructose and (3) maltase breaking down maltose into two glucose molecules (Ibid). The
monosaccharides from dietary carbohydrates do not require further digestion in order to be
11
absorbed. The indigestible carbohydrates continue into the large intestine and will be covered in the
section concerning fibers.
Fructose is absorbed through a facilitated diffusion, where a carrier protein is used to move the
fructose down a concentration gradient. Concentration gradient occurs when the difference of the
concentration inside and outside the cell, forces the nutrient into the absorptive cell (ByrdBredbenner et al., 2012, p. 132). Glucose and galactose are absorbed by an active absorption; an
active absorption involves a carrier protein and ATP in order to move glucose and galactose,
against the concentration gradient and into the absorptive cells (Byrd-Bredbenner et al., 2012, p.
132). The nutrients can be transported against the concentration gradient due to the sodiumpotassium pump, which uses ATP to transport Na+ and K+ ions through the membrane from an area
of low concentration into an area with high concentration (Byrd-Bredbenner et al., 2012, p. 488).
This makes it possible for glucose and galactose to be pumped into the absorptive cells along with
sodium. When the monosaccharide’s enters the intestinal cells they are transported into the liver
through the portal vein. In the liver fructose and galactose are converted into glucose. The glucose
is then transported to the cells, for energy use, through the bloodstream. The remaining glucose is
stored as glycogen in the liver and muscles (Byrd-Bredbenner et al., 2012, p. 172).
3.2.4. Dietary fiber
Fibers are composed of non-starch polysaccharides, which enables them different properties and
functions (Byrd-Bredbenner et al., 2012, p. 157). Not only do they differ in structure from simple
carbohydrates, but they also differ in their digestion process.
3.2.4.a. Digestion
The digestion of fibers begins in the large intestine because of the β-bonds, which cannot be broken
down by the human enzymes. When the indigestible polysaccharides reaches the large intestine,
they are fermented by bacteria into short-chain fatty acids, gas or excreted into fecal waste (ByrdBredbenner et al., 2012, p. 171). The short-chain fatty acids are mainly fermented by soluble fibers
and produce fuel for the cells, in the large intestine, and enhance intestinal health (Byrd-Bredbenner
et al., 2012, p. 157).
12
3.3. Gastric emptying
The rate of gastric emptying is determined by several factors, such as the amount of food, the
nutrients, the structure of the food and hormones (Geissler & Powers, 2005, p. 56). Looking at the
structure of the food liquids empty more rapidly, from the stomach, than solid The rate the liquid is
emptied is in constant proportion with the liquid volume in the stomach, meaning that the rate of
400 mL is twice the rate of 200 mL liquid foods (Shils, Shike, Ross, Caballero, & Cousins, 2006, p.
1181). Furthermore the rate is influenced by: the tonic contractions, the pyloric sphincter resistance
and the duodenums capacity to receive liquid. The rate of gastric emptying is further influenced if
the liquid contains nutrients, due to feedback from the small intestine: thus the caloric
concentration, the pH-value, osmolality and fat content affect the rate (Ibid). High energy density
liquids empty in a lower rate than liquids with fewer calories, as the approximate rate for nutrients
entering the small intestine is 200 kcal per hour (Ibid). A natural liquid empty faster than an acid
liquid, due to the pH difference in the stomach and small intestine. Acid liquids are slowed in order
to prevent a change in the small intestine pH-value and thereby maintaining the environment for the
pancreatic enzymes (Ibid). Carbohydrates and amino acids regulate the nutrient delivery, through
their effect on the small intestine osmolality. Liquids with high osmolality empty slower than
liquids with low osmolality, meaning an l00 mL liquid with 0.1 M empties twice as fast as a 100
mL liquid with 0.2 M (Ibid). Liquid containing fat is emptied more slowly compared to aqueous
liquid, due to fat binding to solid food particles, thus floating on the surface of aqueous gastric
secretion (Ibid). Furthermore lipids inhibits gastric motility, as the hormone signals appearing,
when nutrients enters other parts of the gut (Geissler & Powers, 2005, p. 56). Luminal lipids
stimulate the release of CCK, peptide YY (PYY), glucagon-like peptides (GLP) and neurotensin.
CCK has local effects on the gastric motility, as it stimulates the intestines afferent nerve pathways,
resulting in inhibition of gastric activity. PYY is released when short-chain fatty acids are sensed in
the ileum, which inhibit gastric motility (Ibid).
The gastric emptying of digestible solids occurs at a slower rate than liquids. Before
the solids can pass the pyloric sphincter, the food particles diameter needs to be reduced into a
maximum of 1-2 mm. This process occurs in the lag phase; here the particles are grinded and
mixed. The smaller the particles are the shorter is the lag phase; it can continue up to an hour after
the meal. After the lag phase the particles are emptied in a linear rate and in contrast to liquids the
rate is independent from the volume in the stomach. Solids larger than 2 mm after the lag phase are
emptied from the stomach by the stomach's active contractions (Shils et al., 2006, p. 1181).
13
3.4. Thermic effect of food
Macronutrients have different thermogenic values, due to their different ways of digestion,
absorption, transportation, storage and metabolization. The thermic effect of food is the amount of
energy used to handle the food we consume also known as TEF. This value can account for as much
as 10% of our total energy intake, used to digest and absorb etc. This value may of course be
different within individuals and even for different meal compositions, as the macronutrients demand
different needs of energy for metabolization (Byrd-Bredbenner et al., 2012, p. 317):
TEF for fat 0-3%
(Ibid)
TEF for protein - 20-30%
(Ibid)
TEF for carbohydrates 5-10%
(Ibid)
These values are simply due to the structure and functions of the macronutrients, for example it is
more energy demanding to metabolize amino acids into fat, compared to transferring absorbed fat
into the body's fat storage (Ibid).
3.5. Satiety
Satiety is influenced by a multitude of factors; therefore six general concepts need to be clarified, in
order to get a better understanding of the biological and physiological processes that affect food
consumption. The first concept is Hunger, which is the biological and physiological drive that
indicates that the body needs food. It is the organs, hormones, metabolic influences and the nervous
system that mainly controls hunger (Byrd-Bredbenner et al., 2012, p. 321). The second concept that
needs a calcification is satiation, which is the feeling of fullness developed during a meal, therefore
satiation tend to bring the eating episode to an end. Satiation is also referred to as intrameal satiety,
because it both reduces hunger and the energy consumed during the meal (Gerstein et al., 2004).
The third concept is satiety, which is the fullness developed after the eating episode. Satiety is also
referred to as intermeal satiety, because it delays the resumption of eating. Satiety is also commonly
referred to as both intra- and inter-meal (Ibid), which is the definition used in this thesis. The fourth
concept is appetite. Appetite is the psychological influences that drive the human to eat. It is
primarily affected by external factors, such as social influence, emotions, preferences or aversions
and environmental factors (Byrd-Bredbenner et al., 2012, p. 321). The fifth concept is sensory
14
specific, which is the change in hedonic response to the sensory properties of the food consumed
(Gerstein et al., 2004). Lastly the concept satiety index score (SI%) is the value of subjects satiety
ratings based on the food consumptions (Ibid).
The relationship between the first four concepts can be explained through feelings, perceptions,
observed behavior and operations. When feeling hunger the urge to eat begins, which lead to the
observed behavior of eating a snack or a meal. This operation results in the initiation of an eating
episode (Blundell & Burley, 1987). Satiation then weakens hunger, which results in the eating
coming to an end. This operation is referred to as the termination of the eating episode (Ibid).
Appetite begins with the perceived pleasantness of the food and the evaluation of the taste, which
leads to the observed behavior of selecting food, change of the eating rate and results in the
maintenance of eating (Ibid). Lastly satiety is when there is no wish to eat, which lead to the
observed behavior of resistance to further eating. This operation results in inhibition of eating
(Ibid). The feelings, perceptions, observed behavior and operations could explain why hunger and
appetite do not always correspond to the feelings of satiation and satiety. In some situations a dish
is served that evokes the appetite and the eating is maintained or begins even though the feeling of
fullness already has occurred. Other times when feeling hungry the food served do not evoke the
appetite and the eating does not begin (Byrd-Bredbenner et al., 2012, p. 321).
3.5.1. The biological process of satiety
The process of satiety is mainly regulated through the hypothalamus. The hypothalamus is affected
by internal signals from different hormones and transmitters, which among others affect satiety
(Byrd-Bredbenner et al., 2012, p. 322). The first factor, which elicits satiety, is the sensory aspect of
the food eaten, such as smell, flavor and portion size, followed by the knowledge of the food that
has been eaten (Ibid). Secondly the stomach and intestines expand; low-energy dense foods, with a
high content of water and fiber, causes a greater expansion compared to high-energy foods, such as
snacks and oils (Ibid). Lastly the secretion of different hormones during the digestion, absorption
and metabolism contribute to the promotion of satiety (Ibid). The hormones influence on satiety is
not fully understood, however some gut hormones are known to affect satiety (Murphy & Bloom,
2006). Ghrelin is the only known hormone, which increases appetite, and is therefore often referred
to as the hunger hormone. Ghrelin is a peptide hormone that is released from the stomach. It’s
levels increases during fasting and decreases after a meal (Ibid). When the levels of ghrelin is
15
regulated it signals to the hypothalamus, resulting in the feeling of hunger during a fasting state or
the promotion of satiety after a meal (Byrd-Bredbenner et al., 2012, p. 322). CCK reduces food
intake and is secreted from the small intestine after a meal. It seems that cholecystokinin signals,
the reduction of food intake, through the vagal nerve (Murphy & Bloom, 2006). PYY and
oxyntomodulin (OXM) are secreted from the large intestine after a meal, thus the secretion is
reduced during fasting. They reduce food intake and signals to the hypothalamus; furthermore they
might signal through the vagal nerve (Ibid). Glucagon-like peptide-1 (GLP-1) is, as PYY and OXM,
released through the large intestine and signals to the hypothalamus and possible through the vagal
nerve. GLP-1 is released after a meal and reduces hunger; additionally GLP-1 is an incretin, thereby
stimulating insulin secretion (Ibid). Pancreatic polypeptide (PP) also reduces hunger and is released
from the pancreas after a meal. PP signals to neurons in the brainstem (Ibid). Lastly the hormone
leptin has an effect on satiety. It is not a gut hormone, but is produced by the adipose tissue. Leptin
signals satiety to the hypothalamus, thus ghrelin works as an antagonist to leptin (Longenbaker,
2014).
3.6. Scales
Appetite and satiety are often measured as subjective sensations; this makes the measurements and
methods vulnerable to both external and internal influences. Physiological and psychological
factors may prove to be of great concern when conducting studies, where reproducibility is of the
utmost importance. Here it is central to minimize the factors that could alter the results; this could
be done, by excluding restrained eaters or subjects participating in a weight loss. These participants
might however be included, if the study would provide a standardized diet prior to the intervention
(Flint, Raben, Blundell, & Astrup, 2000). External factors that might influence the results of a given
method or test have to be controlled and kept constant, to the best of the abilities, in order to
produce valid results. Herein several things must be of concern on test days and the day/days
leading up to the test, for example; physical activity, alcohol and food intake. This is essential for
reproducibility of the standardized method to be possible (Ibid).
3.6.1. Visual analogue scales
Visual analogue scales (VAS) are popularly used in scientific studies to measure subjective
sensations, such as appetite. The VAS is set up as a line with a specific length, containing a
16
statement at each end of the line. The statements at each end are set up as opposites or negative and
positive statements, for example; I am not full at all vs. I am very full. The test subjects are then to
set a mark at their current state, which can be analyzed. As VAS is the main method for satiety
ratings in our included literature, it is important that the VAS actually measures the factor, which it
is intended to. It is therefore essential that the method is considered valid. In order to inspect the
VAS method, the study by Flint et al. (2000) has been examined.
In the study by Flint et al. (2000) the VAS was tested on 55 healthy, normal weight men from the
age of 19 to 36. The objective was to test the reproducibility and validity of the VAS measurements
on appetite sensations, such as hunger and fullness. Flint et al. (2000) found that there was
substantial variation in the underlying data that was gathered; this was accounted for as biological
and methodological variation. This variation was not deemed as unexpected, as the measurements
were concerning subjective feelings. The study concluded that disregarding the mentioned
variations, VAS is a valid and reproducible method when concerning appetite ratings and that all
appetite parameters seemed to correlate to post energy intake (Ibid).
3.6.2. Seven-point bipolar equilateral rating scales
The second rating scale method used was a seven-point bipolar equilateral rating scale (7-point). In
this type of scale, one is able to use seven or fewer statements on a bipolar scale, which measures in
two directions such as; "not at all" to "extremely”. On the subject of hunger and satiety, an example
would be; "not at all hungry" to "extremely hungry". It is important to inquire with a balanced
amount of positive and negative statements, in order to reduce response bias and increase validation
of the method (Fischer, Colombani, & Wenk, 2004). The 7-point scale has been suggested to create
greater retest reproducibility than the VAS, when used on satiety and being easier to understand and
use; it was therefore viewed as a compatible method (Holt, Brand Miller, Petocz, & Farmakalidis,
1995).
4. Results
In the following section a brief overview of the 10 included studies and their methodology will be
presented, followed by a descriptive matrix and a summery of the results.
17
4.1 Methodology
All studies recruited their participants in different manners. Some studies included both sexes, while
others only included one. All participants were screened before inclusion, in order to exclude
factors that could influence the study. Exclusion criteria for all the studies were among others;
smokers, obese, restrained eaters and participants with any form of medical condition/illness. This
made the included participants more streamlined and made the results comparable across the studies
(Gregersen et al., 2011).
4.1.1. Study design and procedure
The included studies had comparable designs and procedures. They were all designed as within
subject or cross-over designs, were every participant tried each of the test meals; this increased the
strength and validity of each study (Flint et al., 2000).
All studies had at least one day in between test days, in order to eliminate bias from previous tests.
Furthermore all test meals, except the one by Perrigue, Monsivais, & Drewnowski (2009), came in
the form of breakfast, followed by an ad libitum lunch/dinner; details of test meals and subsequent
meals can be viewed in the matrix. Participants were to cease strenuous exercise prior to the test
day and refrain from caffeine and alcohol, some studies included pre-packaged dinners on the
evening before the test day - this was however not a criteria for all studies, neither was it seen as a
critical factor for allowing comparison (Flint et al., 2000). Before a test day, the subjects were
fasted with a minimum of eight hours. At arrival the participants were screened for compliance
before presentation of the test meal as well as assessed for hunger and other parameters. Subjective
hunger ratings were assessed, by using the VAS Score, except the one study by Fischer, Colombani,
& Wenk (2004), who used the 7-point score. Both methods are deemed as valid and reproducible
(Holt et al., 1995). The different studies did however have different times for when to conduct
measurements and when to serve the different test meals. Some studies also included other
parameters than the standard hunger and fullness, if relevant this will be shown in the result
summary.
In order to make the results from the included studies more comparable to each other, the authors of
this thesis have redefined the name of the different test meals. The renaming of the test meals has
been done in accordance to the NNR recommendations of macronutrient intake. The definitions are
18
as following: low fat <25E%, high fat >40E%, low protein <10E%, high protein > 20E%, low
carbohydrate <45E%, high carbohydrate >60E% and high fiber >3/MJ (Nordic Council of
Ministers, 2008, pp. 25–27). Fiber is only defined as high, due to the fixed recommendation by
NNR, which makes it difficult to define low/moderate range. Furthermore this thesis defines
significance as a p-value of ≤0.05.
4.2. Matrix
M: Male
HF: High fat
W: Women
LF: Low fat
Age: Years
BMI: Kg/m
HP: High protein
2
LP: Low protein
PDS: Prior diet standardization
HC: High carbohydrate
F: Fat
LC: Low carbohydrate
P: Protein
HFi: High fiber
C: Carbohydrate
HR: Hunger rating
Fi: Fiber
SM: Subsequent meal
Q: Quantity (g/mL)
*: Data for males/females
-: No data
+: The study contains two experiments
Bold text: marks the superior diet
↑ indicates significant higher rating/intake compared with other test meals
↓ indicates significant lower rating/intake compared with other test meals
→ indicates no significant difference between the test meals
19
Tabel 3 - Matrix
Study
Design
Clegg &
Randomized
Shafat
, balanced,
2010
Participants
Intervention
No.
Sex
Age
BMI
9
M
25.5
-
PDS
Test meal
F: 70%, P: 7%, C: 25%, Fi: 1.2 g,
Result
Meal name
HF/LP/LC
Q: 222 g, Kcal: 771
HC vs. HF/LP/LC & HF: 
single-blind
F: 29%, P: 11%, C: 65%, Fi: 1.2 g,
(p<0.05)
study
Q: 357 g, Kcal: 789
± 1.6
HC
F: 43%, P: 13%, C: 47%, Fi: 1.2 g,
Cotton,
Within-
Burley,
subject
Weststra
design
16
------
M
-------
HF vs. HC:  (p<0.01)
HF
Dropout: 0%
LF/HC
HR 3h:
22.87
F: 23%, P: 11%, C: 70% Fi: -
0.35
± 0.46
Q: 580 g, Kcal: 440
------------
F: 57%, P: 6%, C: 39%, Fi: -
LF/LP/HC vs. HF/LP/LC: 
HF/LP/LC
12
M
(p=0.03)
LF/LP/HC vs. LF/HC: 
Q: 640 g, Kcal: 803
te, &
1994
SM: Fixed & Ad libitum
21.06 ±
---------
HR 7hr: 
SM:
Q: 222 g, Kcal: 438
Blundell,
HR 3hr:
LF/LP/HC
LF/HC vs. HF/LP/LC: 
23.4
22.87
F: 13%, P: 6%, C: 86%, Fi -
± 0.9
± 0.46
Q: 735 g, Kcal: 803
HR 10h: 
SM: Ad libitum
SM: 
-----------------------HR 2h:
LF/LP/HC vs. HF/LP/LC &
LF/HC:  (p<0.01)
LF/HC vs. HF/LP/LC: 
SM:
20
LF/LP/HC vs. HF/LP/LC: 
(p<0.02)
LF/LP/HC vs. LF/HC: 
(p<0.04)
LF/HC vs. HF/LP/LC: 
Dropout: 0 %
40
M, W
27 ± 5
Dougkas
Randomized
24.3 ± 1.6
X
F: 63%, P: 9%, C: 28%, Fi: -
&
, within-
*Q: 667/533 g, *Kcal: 502.3/402
Ostman,
subjects, 2-
F: 42%, P: 40%, C: 19%, Fi: -
2016
level
*Q: 667/533 g, *Kcal: 502.3/402
factorial
F: 20%, P: 9%, C: 71%, Fi: -
design
*Q: 667/533 g, *Kcal: 502.3/402
F: 13%, P: 40%, C: 47%, Fi -
HF/LP/LC
HR 3.5h: 
SM: 
HF/HP/LC
Dropout: 10%
LF/LP/HC
LF/HP
*Q: 667/533 g, *Kcal: 502.3/402
F: 25%, P: 24%, C: 50%, Fi: -
HP
*Q: 667/533 g, *Kcal: 502.3/402
SM: Ad libitum
Fallaize,
Randomized
31
M
21.7
23.1
± 1.15
± 2.65
F: 57%, P: 23%, C: 23%, Fi: -
Wilson,
, 3-way
Gray,
crossover
F: 26%, P: 11%; C: 64%, Fi: -
Morgan,
design
Q: -, Kcal: 331
HF/HP/LC
HR 3h:
HF/HP/LC vs. HF/LP: 
Q: -, Kcal: 327
HC
(p<0.05)
HF/HP/LC vs. HC: 
HF/LP
HF/LP vs. HC: 
&
F: 49%, P: 6%, C: 46%, Fi: -
Griffin,
Q: -, Kcal: 328
HR 8.5h: 
2013
SM: Ad libitum
SM:
HF/HP/LC vs. HF/LP: 
(p=0.03)
Dropout: 3%
21
17
M
26.5
Fischer
Repeated
21.9 ± 1.7
X
et al.,
measures,
2004
counterbalan
F: 0%, P: 100%, C: 0%, Fi: -
ced cross-
Q: 400 mL, Kcal: 400.8
over design
F: 100%, P: 0%, C: 0%, Fi: -
± 3.3
20
M, W
24.1
F: 0%, P: 0%, C: 100%, Fi: -
LF/LP/HC
LF/HP/LC vs. HF/LP/LC: 
Q: 400 mL, Kcal: 400.8
21.7 ± 2.2
LF/HP/LC
(p<0.001)
LF/HP/LC vs. LF/LP/HC: 
HF/LP/LC
(p<0.05)
400 mL, Kcal: 400.8
SM: 
SM: Ad libitum
Dropout: 12%
Kristens
Open-
F: 34%, P: 21%, C: 45%, Fi: 3.6 g
en et al.,
labeled
2010
randomized
F: 28%, P: 20%, C: 52%, Fi: 11.7 g
multiple
Q: 181.4 g, Kcal: 480
crossover
F: 35%, P: 21%, C: 44%, Fi: 2.2 g
design
Q: 213.5 g, Kcal: 480
± 3.8
HR 2.45h:
HP
SM: 
Q: 169.9 g, Kcal: 480
F: 31%, P: 21%, C: 48%, Fi: 5 g
HR 3h: 
HFi
Dropout: 20%
HP
HP
Q: 227.2 g, Kcal: 480
SM: Ad libitum
Perrigue,
Within-
40
M, W
-
-
X
F: 12%, P: 11%, C: 60%, Fi: 6 g
Monsiva
subject,
472 mL, Kcal: 440
is, &
counterbalan
F: 12%, P: 11%, C: 60%, Fi: 0 g
Drewno
ced design
Q: 472 mL, Kcal: 440
LF/HFi
HR 2h:
LF/HFi, LF, LF/HP/LC/HFi
LF
& LF/HP/LC vs. LF/LP/HC: 
(p<0.05)
wski,
F: 0%, P: 27%, C: 40%, Fi: 6g
LF/HP/LC/H
SM:
2009
Q: 472 mL, Kcal: 180
Fi
Dropout: 5%
F: 0%, P: 27%, C: 40%, Fi: 0 g
LF/HP/LC
Q: 472 mL, Kcal: 180
F: 0%, P: 0%, C: 98%, Fi: 0 g
LF/LP/HC
Q: 472 mL Kcal: 180
SM: Ad libitum
22
Poppitt,
Randomized
12
W
-
-
X
F: 19%, P: 11%, C: 68%, Fi: -
Mccorm
, Within-
Q: 712 g, Kcal: 528
ack, &
subject
F: 69%, P: 11%, C: 21%, Fi: -
Buffenst
design
Q: 732 g, Kcal: 504
ein,
F: 19%, P: 59%, C: 20%, Fi: -
1998
Q: 786 g, Kcal: 456
LF/HC
HR 2h: 
SM:
HF/LC
LF/HP/LC vs. LF/HC &
HF/LC:  (p<0.05)
LF/HP/LC
Dropout: 0 %
LF/HC
HR 3h: 
SM: Ad libitum
Rolls et
Within-
al., 1991
subjects,
28
M, W
M: 26.4
-
± 4.1
F: 5%, P: 14%, C: 81% Fi: -
repeated
F: 65%, P: 15%, C: 20%, Fi: F: 25.2
measures
W
Dropout: 0%
HP
HR 2h:
SM: Ad libitum
Rolls,
Within-
Hetherin
subject,
gton, &
counterbalan
F: 8%, P: 9%, C: 70%, Fi: -
Burley,
ced design
Q: 390 g, Kcal: 300.3
1988
10
HF/LC
*Q: 500/350 g, *Kcal: 510/357
± 4.4
design
SM: 
*Q: 500/350 g, *Kcal: 510/357
23.1
21.0
± 4.1
± 1.13
F: 25%, P: 75%, C -, Fi: Q: 210 g, Kcal: 298.3
F: 97%, P: 5%, C: - Fi: -
HP, LF/LP/HC, HF/LP & LP
LF/LP/HC
LF/LP/HC & HP vs. HF/LP: 
HF/LP
LP/HC
Q: 94 g, Kcal: 299.8
F: 38%, P: 5%, C: 60%, Fi: -
(p<0.01)
LF/LP/HC & HP vs. LP:  (p
Q: 66 g, Kcal: 289.7
F: -, P: 2%, C: 91%, Fi:
vs. LP/HC:  (p<0.01)
< 0.01)
SM:
LP
LF/LP/HC & HP vs. HF/LP,
Q: 68 g, Kcal: 299.9
LP/HC & LP:  (p<0.05)
SM: Ad libitum (Lunch)
Dropout: 0 %
23
4.3. Satiety
This section summarizes the results of the test meals effect on hunger, fullness and subsequent meal
intake. These measurements will be stated according to their relation to satiety and whether or not
they were deemed significant. It must be mentioned that the procedure and questionnaires vary
within the different studies.
4.3.1. Hunger
All the studies investigated the combination between hunger ratings and different macronutrient
intake. Six studies found a significant difference between the macronutrients and the hunger
ratings. Moreover the significant difference was only found within a 3-hour period.
Clegg & Shafat (2010), found that a high carbohydrate (HC) meal reduces hunger, to
a higher extent, than a meal high in fat, low in protein and low in carbohydrates (HF/LP/LC) or than
a meal high in fat (HF) (p<0.05). However the differences in hunger was only significant within the
first 3 hours. According to Cotton et al. (1994), experiment 1, a meal low in fat and in protein and
high in carbohydrate (LF/LP/HC) reduces hunger more than a HF/LP/LC meal (p=0.03). However
as in Cleeg’s study, there was only a significant difference, between the test meals, during the first 3
hours. In experiment 2, Cotton found a decrease, within a 2-hours range, in hunger after a
LF/LP/HC meal compared to a HF/LP/LC meal and a low fat, high carbohydrate (LF/HC) meal
(p<0.01). Fallaize et al (2013) found that a high fat, high protein and low carbohydrate (HF/HP/LC)
meal decreases hunger to a higher extent than a meal high in fat and low in protein (HF/LP)
(p<0.05); although the significant difference was only valid within a 3-hour range. According to
Fischer et al. (2004) a low fat, high protein and low carbohydrate (LF/HP/LC) meal reduces hunger
more than a HF/LP/LC meal (p<0.001) and a LF/LP/HC meal (p<0.05). Perrigue et al. (2009) found
a lower reduction in hunger after a LF/LP/HC meal compared to a low fat, high fiber (LF/HFi), a
low fat (LF), a low fat, high protein, low carbohydrate, high fiber (LF/HP/LC/HFi) and a low fat,
high protein, high carbohydrate (LF/HP/HC) meal (p<0.05). Rolls et al. (1988) found a decrease in
hunger after a high protein (HP), a high, fat, low protein (HF/LP), a LF/LP/HC and a low protein
(LP) meal compared to a low protein, high carbohydrate (LP/HC) meal (p<0.01). Furthermore the
LF/LP/HC and HP test meals did result in a higher decrease in hunger compared to a HF/LP
(p<0.01). Lastly Rolls et al. (1988) found that a LF/LP/HC and a HP had a higher effect on hunger
24
compared to a LP meal (p<0.01). Dougkas & Ostman (2016), Kristensen et al. (2010), Poppitt et al.
(1998) and Rolls et al. (1991) found no significant difference between the compared test meals.
4.3.2. Fullness
Nine of the included studies investigated the macronutrients effect on fullness. Six studies found a
significant difference between the macronutrients and their effect on fullness. Similar to the
findings of hunger, the effect only occurred within a 3-hour range.
Clegg & Shafat (2010) showed a similar result to hunger on fullness; HC was rated
higher than HF on their 3-hour rating (p<0.05). Cotton et al. (1994) found no effect on fullness from
the 10-hour rating, however the 3-hour rating did show a significant difference between the
LF/LP/HC and the HF/LP/LC (p=0.03), as LF/LP/HC resulted in increased fullness. Fullness was
not measured in experiment 2. Dougkas & Ostman (2016) managed to find a significant difference
on the 3,5 hour fullness rating between HF/LP/LC and LF/HP (p=0.03), where LF/HP increased the
fullness rating. Fallaize et al. (2013) fullness rating results were different, when comparing
HF/HP/LC and HF/LP (p<0.05), as HF/HP/LC gave a greater rating of fullness from the subjects.
Perrigue et al. (2009) found that a LF/LP/HC meal resulted in a lower 2-hour rating of fullness
compared to a LF/HFi, a LF, a LF/HP/LC/HFi and a LF/HP/LC meal (p<0.05). Furthermore the
subject was less full after a LF/HP/LC meal compared to a LF/HFi and a LF/HP/LC/HFi meal
(p<0.05). Rolls et al. (1988) compared HP and LF/LP/HC vs. LP/HC and HF/LP, LP and found that
HP and LF/LP/HC increased fullness significantly in the 2-hour period (p<0.05). Kristensen et al.
(2010), Poppitt et al. (1998) and Rolls et al. (1991) found no difference in the test meals effect on
fullness. No data was found in Fischer et al. (2004).
4.3.3. Subsequent Meal Intake
The different test meals effect on subsequent meal intake was measured in all the included studies.
Four studies found a significant difference between the macronutrients and subsequent meal intake.
Similar to the other results the effect only occurred within a 3-4-hour period.
Clegg & Shafat (2010) found a significant effect on the subsequent meal intake
between the HF test meals, which caused a higher energy intake than the HC test meal (p<0.01). In
the study by Cotton et al. (1994) the two experiments provided different results; in experiment 1
there was no difference in the subsequent meal intake between the test meals, however in
25
experiment 2 the LF/LP/HC test meal led to a reduced energy intake compared to the HF/LP/LC
(p<0.02). Furthermore the LF/LP/HC test meal also led to a reduced energy intake in comparison to
the LF/HC (p<0.04). Fallaize et al. (2013) found a significant effect between two of their test meals;
HF/HP/LC proved to result in a lower energy intake in the subsequent meal, when compared to the
HF/LP (p=0.03). Poppitt et al. (1998) also showed a significant difference between their LF/HP/LC
vs. the LF/HC and high fat, low carbohydrate test meal (HF/LC) (p<0.05), here the LF/HP/LC test
meal resulted in a reduced subsequent meal intake at lunch. Rolls et al. (1988) discovered a
different effect between the LF/LP/HC and HP vs. the HF/LP, LP/HC and LP (p<0.05), as the
LF/LP/HC and HP resulted in a lower subsequent meal intake. Dougkas & Ostman (2016), Fischer
et al. (2004), Kristensen et al. (2010), Perrigue et al. (2009) and Rolls et al. (1991) found no
difference on the test meals effect on subsequent meal intake.
4.4. Other parameters
When assessing satiety other parameters than hunger, fullness and subsequent intake were
measured. Seven of the included studies measured on the subject's desire to eat and the
pleasantness of the test meals. Six studies measured the prospective consumption and two studies
included gastric emptying as a parameter.
4.4.1. Desire to eat
Four out of seven studies found a significant difference, of the subjects desire to eat, after the test
meals. Two studies found no difference after the test meal and lastly no data was found in the study
by Kristensen et al. (2010). Clegg & Shafat (2010) found that a HC meal resulted in a lower desire
to eat compared to a HF meal (p<0.05), however there was only found a significant difference
within the first 3-hours. Likewise Cotten et al. (1994), experiment 2, showed a lower desire to eat
after a LF/HP/HC meal compared to a LF/HC and a HF/LP/LC meal (p<0.05). A LF/HP/LC meal
resulted in less desire to eat compared to a HF/LP/LC meal (p<0.01) in the study by Fischer et al
(2004). According to Perrigue et al. (2009) a LF/HFi meal result in a lower desire to eat compared
to the LF/LP/HC test meal (p<0.05). Dougkas & Ostman (2016) and Rolls et al. (1991) found no
difference between the test meals and the subject's desire to eat.
26
4.4.2. Pleasantness
There is an overall agreement, within the studies measuring, on the test meals pleasantness. Five out
of the seven studies found no difference on the pleasantness of the test meals, these studies includes
Cotton et al. (1994), Dougkas & Ostman (2016), Kristensen et al. (2010), Poppitt et al. (1998) and
Rolls et al. (1991). No data was found in the studies by Clegg & Shafat (2010) and Fischer et al
(2004).
4.4.3. Prospective consumption
Three out of the six studies found no difference in prospective consumption. One study found
significance and lastly in the studies by Cotton et al. (1994) and Fischer et al. (2004) no data was
found. Fallaize et al. (2013), Kristensen et al. (2010) and Rolls et al. (1991) was in agreement and
found no difference in the prospective consumption after the test meals. Dougkas & Ostman (2016)
on the other hand found that a LF/HP and a HF/HP/LC meal resulted in a lower rating of
prospective consumption compared to a LF/LP/HC meal (p<0.05)
4.4.4. Gastric emptying
Two studies investigated gastric emptying after the test meals. Clegg & Shafat (2010) found that a
HF/LP/LC meal slowed gastric emptying compared to a HF (p<0.05) and a HC (p<0.01) meal.
Likewise Fischer et al. (2004) showed a HF/LP/LC meal slowed gastric emptying compared to a
LF/HP/LC (p<0.01) and a LF/LP/HC (p<0.05) meal.
5. Discussion
This thesis investigated the macronutrients effect on satiety. Looking at the results from the
literature, the answer to the research question is inconclusive, however the results suggest that
protein might be superior, compared to the other macronutrients. In order to conclude on the results,
procedures and limitations will be discussed and investigated to see whether other factors have
influenced the results.
27
Fat & Satiety
In the study by Clegg & Shafat (2010) two different high fat meals were tested: HF/LP/LC and HF.
Both of these were significantly less effective in decreasing hunger when compared to a HC test
meal (p<0.05). The measurements on fullness also showed the HF test meal to be less effective
when compared to the HC (p<0.05), moreover the HF test meal increased intake at the SM
compared to the HC (p<0.01). The results from Clegg & Shafat (2010) would indicate that fat, as a
macronutrient, has an inferior effect on satiety compared to carbohydrate. However components of
the included test meals were more complex than just macronutrient composition; the test meals also
differed in quantity and calories. Within these differentials, quantity and portion size may come in
to play, as it can affect the following food intake and satiety. This was shown by Kral (2006), who
found a significant correlation between portion size and satiety. The effect of portion size would
seem to be present in Clegg & Shafat (2010), as the most satiating of the three test meals, the HC,
was also the heaviest with 135g more than the others; this would cause greater gastric distention
and may have been the reason for the decreased hunger, increased fullness and decreased SM intake
compared to the HF test. The HF/LP/LC and HF test meals did however not differ in quantity, but
in calories, which did not seem to significantly influence the results even though the difference was
333 calories. It would therefore appear that not only is fat less satiating than carbohydrate, but also
that meal quantity is more effective in influencing satiety than meal energy content.
The results from Clegg & Shafat (2010) can be confirmed by Cotton et al. (1994),
who came to similar results in their study. In both experiment 1 and 2 the hunger rating of the
HF/LP/LC test meal was significantly less effective compared to the LF/LP/HC (p=0.03 & p<0.01)
and showed no effect, when HF/LP/LC was compared to the LF/HC. In experiment 1, fullness also
decreased in the HF/LP/LC vs. the LF/LP/HC (p=0.03), but the SM intake did however not differ
between the test meals. At first it would seem that there might not be a correlation between hunger,
fullness and SM intake. However when examining the study procedure, one will notice the longer
time interval between the test meals and lunch, compared to experiment 2. The results from
experiment 2, could indicate that the satiety abilities of a meal only lasts for a short period of time
as the HF/LP/LC had a significantly higher SM intake compared to the LF/LP/HC (p<0.02) in a 2hour period, but did not differ from LF/HC. This outcome confirms the limited suppression fat has
on satiety in the short-term, compared to a high carbohydrate meal. Once again it should taken into
consideration, that there are relative differences in quantity between the meals; the most satiating
was also the heaviest; LF/LP/HC contained 95g more than HF/LP/LC and 155g more than LF/HC.
28
This would once again pose the hypothesis of portion size being the primary factor. This relation is
also confirmed by Kral (2006), who examined the effect of portion size on satiety and found a clear
correlation between increased portion size leading to increased satiety. Yet HF/LP/LC still showed
no effect for better or worse, when compared to LF/HC in either of the parameters, even though
HF/LP/LC was 60g heavier and contained 363 calories more than LF/HC; an indication of fats
inferior effect on satiety.
Poppitt et al. (1998), were not able to show a significant difference on hunger rating or
fullness rating between the test meals, but did manage to reach significance in SM intake. As to
why there was no measurable effect on hunger and fullness is difficult to determine. However the
HF/LC was shown to increase SM intake compared to LF/HP/LC (p<0.05). As seen in Clegg &
Shafat (2010) and Cotton et al. (1994) the most satiating meal was the heaviest, with 54g between
LF/HP/LC and HF/LC. Yet a test meal dominant in fat content showed to be less effective in
affecting satiety, than a test meal dominant in protein or carbohydrate, as there was found no
significant effect between HF/LC and LF/HC, even though HF/LC was a heavier meal. This
difference should according to Kral (2006) have led to higher satiety from the HF/LC, yet this was
not the case; a similar result was also seen in Fischer et al. (2004).
In the study by Fischer et al. (2004) portion size was not a relevant factor, as the test
meals served were of equal volume and calorie content. The results still showed fat as inferior in
hunger rating when HF/LP/LC was compared to LF/HP/LC (p<0.001), yet no difference between
HF/LP/LC and LF/LP/HC was found. SM meal intake was not significantly different for any of the
test meals. The reason for the lack of significant difference in SM intake might very well be due to
the >3-hour interval between the test meal and lunch. This duration was most likely to long for the
test meals to withhold their short-term difference in satiety; this was also seen in experiment 1, by
Cotton et al. (1994). However the result does indicate for fat having a weaker effect on satiety than
protein, when served in pure macronutrient forms.
Dougkas & Ostman (2016) found a significant effect on the fullness ratings, where
LF/HP increased the fullness compared to the HF/LP/LC. As there was accounted for both quantity
and calorie content this would suggest a superior effect of protein vs. fat. In contrast Rolls et al.
(1991) did not manage to find a significant difference on fullness, which likely is do due to the
comparison concerning high fat vs. high carbohydrate. It would indicate that these two
macronutrients are relatively alike in their effect on fullness, or at least that their abilities are not
significantly different if served in similar quantity and calorie content. Neither study found a
29
difference whatsoever on hunger ratings or SM intake between the test meals, both of these studies
used equal weight and iso-caloric test meals, as well as serving them in a liquid form. The results
somewhat contradict the previous findings and shows no difference in short-term satiety sensations
after consuming fat, protein or carbohydrate-rich test meals. This contradictory result may
nonetheless be due to the form the preloads were served in. It has been seen that liquid forms may
have a weaker effect on satiety, and withhold an even shorter period of effect due to the quicker
gastric emptying of liquids contra solid foods (Shils et al., 2006, p. 1181). This may explain why
the studies were not able to find a significant difference.
Fallaize et al. (2013) and Rolls et al. (1988) had quite different results on fats satiety
capabilities compared to the rest of the included studies. Both studies found high fat test meals to be
superior, when compared to some of the other test meals; this result can however be explained by
other factors than fats influence on satiety. Fallaize et al. (2013) found HF/HP/LC to decrease
hunger compared to HF/LP (p<0.05) and increase fullness compared to HF/LP (p<0.05), HF/HP/LC
also decreased SM intake compared to HF/LP (p=0.03). Both of these test meals were iso-caloric
and high fat, yet one proved to be more effective at increasing satiety than the other. The outcome
may likely be due to the substantial difference in the protein content; 6% in the HF/LP to 23% in
the HF/HP/LC. As seen in the previous studies, fat has a weak influence on satiety, but there is
suggestive evidence towards protein having a strong influence on satiety, which was also seen in
Fischer et al. (2004) and Poppitt et al. (1998).
Rolls et al. (1988)’ results are still similar to the other studies suggesting
fat as a poor influence on satiety. The HF/LP test meal scored lower on hunger and fullness
compared to the LF/LP/HC and HP (p<0.01 & p<0.05). In addition SM intake was also higher
following HF/LP compared to LF/LP/HC and HP (p<0.05); this is in agreement with the previous
literature, suggesting fat as inferior in affecting satiety. The study did in addition show that all test
meals including HF/LP was rated superior in affecting hunger compared to the LP/HC (p<0.01),
however these test meals were extremely different even though they were designed as iso-caloric.
The weight and food-type of the test meals differ considerably, as the most satiating test meals were
almost six and three times heavier than the HF/LP, making portion size a factor; 390g and 210g vs.
66g. Furthermore the food types differed from what would be considered a main meal to snacks;
pasta and chicken vs. cream cheese, Turkish delight and confectionary. This might very well
influence the subjective rating of the food, as sensory properties may influence satiety (Buckland,
James Stubbs, & Finlayson, 2015). With these differences in the test meals, it is difficult to
30
determine the reason behind the results, as it very well may be caused by multiple confounding
factors.
There seems to be a tendency toward high fat meals being less satiating than other macronutrient
composition meals. Clegg & Shafat (2010), Cotton et al. (1994) and Rolls et al. (1988) all showed
that high fat meals were inferior when compared to high carbohydrate meals, in addition Poppitt et
al. (1998), Fischer et al. (2004), Fallaize et al. (2013) and Rolls et al. (1988) showed that this was
also the case when comparing high fat to high protein. Only two studies found no effect on hunger
when comparing the different macronutrient compositions; Rolls et al. (1991) and Dougkas &
Ostman (2016). In order to explain the outcome it is important to shed light upon what might be the
mechanisms resulting in macronutrients different effect on satiety.
Protein & Satiety
Fallaize, et al. (2013) found the HF/HP/LC test meal to reduce hunger and increase fullness
significantly compared to HF/LP (p<0.05 & p<0.05), however no difference between the
HF/HP/LC and the HC test meal was found. In addition SM intake was also decreased after the
HF/HP/LC compared to HF/LP test meal (p=0.03). All three test meals were iso-caloric with
different macronutrient compositions; portion size/quantity was however not mentioned and may
have been a factor. Kral (2006) has previously shown the significant effect of portion size
correlating to satiety; the lack of mentioning this factor in Fallaize, et al. (2013) is therefore a rather
noteworthy limitation. Furthermore test meal type might also have been a confounding factor, as the
subjective rating and perception of the test meals might also influence the result; eggs vs. croissant.
Buckland et al. (2015) has shown that foods not only have an influence on physiological satiety
when eaten, but also on psychological satiety when presented. The very perception of foods ability
to satiate may likely influence any results and ratings and could therefore be a limiting factor when
presenting different foods. However it is still interesting to see that HF/HP/LC was rated more
effective on satiety compared to the HF/LP, as they are both high fat meals, with protein content
being the primary difference. Depending on whether or not quantity and meal type was a limiting
factor this would pose the hypothesis of protein being more satiating than fat.
Fischer et al. (2004) results supported the data by Fallaize et al. (2013), as it showed
protein having a superior effect on hunger, in iso-caloric and iso-volumetric test meals. The
LF/HP/LC reduced hunger compared to both HF/LP/LC (p<0.001) and LF/LP/HC (p<0.05). The
31
test meals did however not differ in their effect on SM intake, as in Fallaize et al. (2013). This is
most likely due to the amount of time between the test meals and lunch, which is longer than 3
hours.
The results from Perrigue et al. (2009) only found a significant difference of hunger
ratings in LF/LP/HC, which was rated higher, in comparison to the rest of the test meals (p<0.05).
This might point toward the satiating effect of protein, as the low protein meal increased hunger
more than all the other test meals. There was conversely no difference between LF/HFi, LF,
LF/HP/LC/HFi and LF/HP/LC in hunger ratings, even though there were differences in both
macronutrient composition and caloric content, none of these were however low in protein. All
meals were of same quantity, which would suggest that if protein content is adequate, then other
factors will have a limited influence on satiety. Fullness was also differential between the meals;
LF/LP/HC decreased fullness compared to LF/HFi, LF, LF/HP/LC/HFi and a LF/HP/LC meal
(p<0.05), in addition LF/HP/LC also decreased fullness compared to LF/HFi and a LF/HP/LC/HFi
meal (p<0.05). It would seem that fullness is not only influenced by protein, but also fiber. Even
though LF/HP/LC was similar to LF/HP/LC/HFi in protein and energy content, it was not as
effective to produce fullness - being that fiber content was the only difference: it would seem that
fiber also affects satiety to a certain degree. SM intake did not differ significantly between any of
the included test meals, which might be due to the time interval between the test meals.
Rolls et al. (1988) supports the results from Fallaize et al. (2013), Fischer et al.
(2004) and Perrigue et al. (2009) and found high protein meals to be superior, compared to other
macronutrient compositions. Hunger ratings resulted in HP decreasing hunger compared to LP/HC
(p<0.01), HF/LP (p<0.01) and LP (p<0.01), while also increasing fullness compared to LP/HC and
HF/LP and LP (p<0.05). Furthermore HP decreased SM intake compared to HF/LP, LP/HC and LP
(p<0.05). These results do show a clear indication of protein being superior in inducing satiety,
however the test meals did differ significantly in weight and food-type, making it difficult to
determine the actual cause for the results, as these factors have previously been seen to affect satiety
(Kral, 2006).
Even though Poppitt et al. (1998) did not manage to find significant differences
between their test meals on hunger and fullness, they still managed to find high protein as superior
in SM intake. LF/HP/LC significantly decreased SM intake compared to both LF/HC & HF/LC
(p<0.05). The high protein test meal would seem to be most effective at inducing satiety, but it was
also the heaviest meal - making a solid conclusion on the effect of macronutrient composition
32
difficult, as the portion size is of strong influence on satiety and could have been the determining
factor creating the significant difference (Kral, 2006).
Dougkas & Ostman (2016) showed a difference on fullness, where protein was
superior: LF/HP vs. HF/LP/LC (p=0.03), but did however not find a difference on hunger or SM
intake between the test meals. The test meals were of equal weight and iso-caloric content, however
served as liquid forms, which may or may not have been the cause for a lack of difference in hunger
and SM intake. The ambiguous part of the result is why LF/HP were the only test meal rated higher
than HF/LP/LC in fullness, as both HF/HP/LC and HP was also high protein meals. HF/HP/LC was
however low in carbohydrate and high in fat compared to the LF/HP, suggesting that carbohydrate
content is more satiating than fat, in addition HP also contained more fat and less protein than
LF/HP, confirming the low satiating power of fat contra both protein and carbohydrate.
Kristensen et al. (2010) found no difference between any of the ratings on hunger, SM
intake or fullness. The included meals were all of different quantity and iso-caloric, furthermore all
but one was high protein. The test meal moderate in protein was still 20% vs. the others containing
21% - making them differ by as little as 1%. In addition both fat and carbohydrate content only
differed within a range of 8%, making the meals fairly similar apart from quantity and fiber content.
It would therefore seem that if protein content is adequate and the macronutrient distribution is
somewhat equal, combined with an iso-caloric energy content, then the satiety parameters would
not differ significantly. In this case Protein content seems to mask the effects of quantity and to a
certain degree making it an insignificant factor concerning satiety. This is however contradictory to
the results from Kral (2006) where portion size was clearly correlated to satiety; yet this result does
indicate the complexity of satiety, as a phenomena and how different factors be of greater
importance than others.
There are strong indications for protein being the most satiating macronutrient, when compared
within test meals. Fallaize et al. (2013), Fischer et al. (2004), Perrigue et al. (2009), Rolls et al.
(1988), Poppitt et al. (1998) and Dougkas & Ostman (2016) all showed superior effects of protein
in either decreasing hunger, increasing fullness or decreasing SM intake compared to fat and
carbohydrate. Kristensen et al. (2010) was the only study, which did not find any effect, however
this was likely due to similar macronutrient composition of the test meals.
33
Carbohydrates & Satiety
In the study by Clegg & Shafat (2010) a HC meal was compared with high fat meals. They found
that a HC meal reduced hunger to a higher extent, within a 3-hour period, compared to a HF/LP/LC
(p<0.05) and a HF meal (p<0.05). Clegg & Shafat (2010) used three similar breakfasts; however the
quantity and the calorie content differed between the three test meals. The higher quantity and
calorie content might be the reason for the HC meal’s reduction in hunger. Interestingly the results
from hunger are not in agreement with the fullness ratings, where no difference was found between
the HC and the HF/LP/LC test meal. This can be explained by the difference in calorie content,
indicating that calories might have an effect on fullness. Another reason could be the difference in
gastric emptying of the foods, as carbohydrates are emptied at a higher rate. Resembling results
were found for the SM intake, indicating that the effect on satiety only exists within a 3-hour
period. The results from Clegg & Shafat (2010) suggest that HC meals are more satisfying than HF,
however it cannot be overruled that the higher satiety is caused by the difference in quantity.
In the study by Cotton et al. (1994) two HC test meals were tested: LF/LP/HC and
LF/HC. Like Clegg & Shafat (2010), the results showed that the LF/LP/HC test meal reduced
hunger compared to a HF/LP/LC meal (p=0.03), moreover no difference was found between the
LF/HC and the HF/LP/LC test meals. Besides this a LF/LP/HC meal reduced hunger compared to a
LF/HC meal (p<0.01) in experiment 2, but no difference was found in experiment 1. Cotton et al.
(1994) used a basis breakfast for all test meals; this basis meal was then adjusted according to the
wished macronutrient composition. The adjustment resulted in difference within the test meals
quantity, where the LF/LP/HC was heavier than the other test meals. Furthermore the LF/LP/HC
test meals contained more calories than the LF/HC. This difference in calories and quantity might
be the reason for the reduction of hunger in the LF/LP/HC test meal. This is supported in the study
by Kral (2006) who found that the portion size influence satiety. Noteworthy is that the LF/LP/HC
test meal had different effects on hunger, when compared with the LF/HC test meal, in experiment
1 and 2. The two experiments had the same meals and same procedures, however the ad libitum
meal was served at different time frames. In experiment 1, the meal was consumed 4 hours and 20
min after the test meal, whereas in experiment 2 it was consumed 2.5 hours after the test meal. The
main difference between the compared test meals was that one was low in protein while the other
had a moderate protein content. This indicates that the protein content might have an effect on how
long a HC meal reduces hunger. This is in agreement with the review by Paddon-Jones et al.
(2008), who found that even a moderate increase of protein might promote satiety. Similar results
34
were found for fullness and SM intake, indicating that there is a correlation between the three
factors. With this Cotton et al. suggest that a LF/LP/HC meal improves satiety to a higher extent
than a HF meal and a LF/HC meal, nevertheless the difference in quantity and protein cannot be
disregarded as an influencing factor, as they both seem to have an influence on satiety.
Dougkas & Ostman (2016) investigates a LF/LP/HC meal and compares it to HF and
HP test meals. In contrast to Cotton et al. no difference was found between the LF/LP/HC and a
HF/LP/LC meals. Furthermore Dougkas & Ostman (2016) found no difference between the
LF/LP/HC test meal and the HF/HP/LC, LF/HP and a HP meal. Similar results were found for
fullness and SM intake. The LF/LP/HC test meals used by Cotton et al. (1994) and Dougkas &
Ostman (2016) has approximately the same macronutrient composition, therefore the reason for the
different results must be found elsewhere. Dougkas & Ostman (2016) compared five iso-caloric and
iso-volumetric liquid preloads and found no difference between the test meals. The explanation for
the different result in the two studies might therefore be explained by the quantity and calorie
content, which differed in the test meals by Cotton et al. (1994) but not in Dougkas & Ostman
(2016). Overall the results by Dougkas & Ostman (2016) suggest that the macronutrient
composition have no effect on satiety. Furthermore it indicates, as Cotton et al. (1994), that there is
a correlation between hunger, fullness and SM intake.
Fallaize et al. (2013) used a HC meal and similar to Dougkas & Ostman (2016), they
found no significant difference between a HC meal and a HF/HP/LC. The same applied for the
HF/LP test meal; similar results were found for fullness and SM intake. Fallaize et al. (2013)
compared three iso-caloric test meals with different macronutrient compositions. The HC test meal
was composed of cereals, the HF/HP/LC of eggs and the HF/LP of croissant. Interestingly no
significant difference was found between the HC test meal and the two HF test meals, even though
the satiety index score (SI%) of the foods, made by Holt et al (1995), are rated differently. HC:
cereal has a SI% of 118±19, the HF/HP/LC: eggs has a SI% of 150 ±31 and HF/LP: croissant has a
SI% of 47 ±17 (Holt et al., 1995). According to these satiety index scores it seems that the quantity
of the test meal should be higher for the HC test meal than the HF/HP/LC test meal, in order to
reach the same satiety rate. Furthermore a lower quantity should be eaten of the HC meal, in order
to achieve the same satiety rating as HF/LP. Unfortunately there is no data on the quantity of the
test meals and the quantity can therefore not be excluded or included as an influencing factor. The
results by Fallaize et al. (2013) suggest there is no difference in satiety when comparing a HC meal
35
with HF/HP/LC and HF/LP meals. Additionally it indicates that there is a correlation between
hunger, fullness and SM intake, as Cotton et al. (1994) and Dougkas & Ostman (2016).
Fischer et al. (2004) investigated LF/LP/HC test meal and found that a LF/LP/HC
meal reduced hunger to a lower extent than a LF//HP/LC (p<0.001). The preloads used by Fischer
et al. (2004) consisted only of one macronutrient and were iso-caloric and iso-volumetric. These
results indicates that a protein meal reduce hunger to an higher extent than carbohydrate, this is in
agreements with the findings by Halton & Hu (2004), who found convincing evidence supporting
protein increases satiety compared to the other macronutrients. Interestingly this result is in contrast
with the findings by Dougkas & Ostman (2016), as it indicates that the macronutrient distribution
might have an effect on satiety. The reason behind this could be that Dougkas & Ostman (2016) did
not use pure macronutrients in their preloads, however the boundary for when the macronutrient
distribution have an effect is unknown. Interestingly there was no difference between the HC test
meal and HP test meal in the SM intake, indicating that the effect on satiety only exist within a 3hour period. The results by Fischer et al. (2004) suggest that HC meals have a lower effect on
satiety than HP, furthermore it indicate that there is no correlation between hunger and SM intake,
within this time frame, as seen in Clegg & Shafat (2010).
Perrigue et al. (2009) used a LF/LP/HC meal when investigating carbohydrates
influence on satiety. In agreement with Fischer et al. (2004), Perrigue et al. (2009) found that a
LF/LP/HC meal reduced hunger less than a LF/HP/LC meal (p<0.05). Furthermore they found the
LF/LP/HC meal to reduce hunger less than a LF/HFi, LF and a LF/HP/LC/HFi meal (p<0.05).
Similar results were found for fullness. The main difference between the LF/LP/HC test meal and
the other test meals is that the LF/LP/HC is orange juice, whereas the others are liquid yogurts.
Since all the test meals is in liquid form, gastric emptying should not be the reason for the
difference in hunger ratings; as gastric emptying of pure liquid occurs in the same rate and it must
therefore be the nutrients in the liquids, that contribute to the difference of hunger. Another factor
that could influence the difference in hunger ratings are the meal type and the pleasantness of the
food, as the subjects are affected by both sensory and cognitive cues, as well as hunger (Kral,
2006). The result of Perrigue et al. (2009) therefore indicates that high protein and high fiber meals
reduce hunger to a higher extent than high carbohydrate meals. Furthermore it indicates that there is
a correlation between hunger and fullness. However no difference was found between the test meals
and SM intake, indicating that the effect of satiety only occurs within a 2-hour range, this is in
agreement with the findings by Clegg & Shafat (2010) and Fischer et al. (2004).
36
Poppitt et al. (1998) found no difference between a LF/HC meal and a LF/HP/LC or a
HF/LC meal. This differentiates from the results of Fischer et al. (2004) and Perrigue et al. (2009),
who found the LF/LP/HC to reduce hunger to a lower extent than LF/HP/LC test meal. This can be
due to several factors, first Poppitt et al. (1998) uses solid food, whereas the others uses liquids,
resulting in a longer gastric emptying for the solid foods, as the lag phase extent this process.
Secondly the test meal by Poppitt et al. (1998) has a moderate protein content, which has shown a
tendency for higher satiety (Paddon-Jones et al., 2008). Similar results were found in fullness
ratings, indicating that there is a correlation between hunger and fullness. Comparable results were
found for the SM intake, however one result contradicts the others. The LF/HC test meal resulted in
a higher intake compared to the LF/HP/LC test meal. This can be due to sensory specific aspects, as
the HC test meals evoked the appetite to a higher extent than the LF/HP/LC, resulting in a higher
intake at the SM. Related findings are found in the study by Kral (2006), when investigating
sensory specific effect on SM intake. Overall the results by Poppitt et al. (1998) suggest that there is
a correlation between hunger and fullness, but not to SM intake.
Similar to Poppitt et al. (1998), Rolls et al. (1991) found no difference between a
HF/LC meal and the LF/HC test meal. The protein content for the two test meals were identical,
therefore only the carbohydrate and fat content differed, showing that there is no variation between
high fat and high carbohydrate meals. Alike results were found for SM intake indicating that there
is a correlation between hunger, fullness and SM intake, as the findings by Cotton et al. (1994),
Dougkas & Ostman (2016) and Fallaize et al. (2013).
Rolls et al. (1998) investigated two HC meals: LF/LP/HC and LP/HC. In agreement
with Dougkas & Ostman (2016), no difference was found between a LF/LP/HC meal and a HP
meal. Furthermore they found that a LF/LP/HC meal reduced hunger significantly more than a
HF/LP meal, a LP and a LP/HC meal (p<0.01). Similar results were found for fullness and SM
intake. Rolls et al. (1998) used iso-caloric test meals. The LF/LP/HC test meal was composed of
pasta and the HP of chicken, no difference was found between these test meals, which is in
agreement with the SI% by Holt et al. (1995), where carbohydrate rich foods SI% are 166±24 and
protein rich foods SI% are 166±13. The LF/LP/HC test meal effect on hunger was rated higher than
the rest of the test meals, which can be due to several factors. First the other test meals were snack
foods, whereas the LF/LP/HC meal was a main dish. Secondly snack foods have in general a low
SI% at 100±10 (Ibid). Lastly the quantity of the other test meals differed, as the LF/LP/HC test
meal weighed more than the HF/LP, LP/HC and LP test meal. The results for the LP/HC test meal
37
showed that a LP/HC reduced hunger to a lower extent than a HP, HF/LP and a LP meal. The
findings are in contrast with results for the LF/LP/HC test meal. One reason for this difference can
be the quantity of the LF/HC that is much lower; this is supported by Kral (2006), who found that
the quantity matter. Another reason could be the difference in fat content in the two HC test meals,
indicating that a moderate fat content in a HC meal might result in a lesser reduction of hunger
compared to a HC meal low in fat. The results for the LP/HC test meal in fullness and SM intake
differed for those in hunger, indicating there is no correlation between hunger, fullness and SM
intake, within the time period. In contrast to the hunger ratings no difference was found on fullness
between the HF/LP and LP test meal compared to the LP/HC test meal. This can be due to different
quantity of the foods, thus the rates of gastric emptying of the specific food become somewhat
similar. The results from Rolls et al. (1998) indicate that the correlation between hunger, fullness
and SM intake might be influenced by the macronutrient composition and quantity.
Carbohydrates influence on satiety is inconsistent. The majority of the studies found no difference
on the carbohydrate test meals, compared to the others. However there seems to be inconsistency in
the carbohydrates effect, within the different types of carbohydrate meals. This indicates that
factors, as macronutrient composition, meal type, quantity and calorie content, might effect the
satiation of the test meal. The studies that found a significant difference between the test meals
showed that a high carbohydrate meal is less satiating than protein, as seen in the studies by Fischer
et al. (2004), Perrigue et al. (2009) and Rolls et al. (1998). Moreover the results showed a tendency
toward fat being less satiating than carbohydrates, as found by Rolls et al. (1998), Cotton et al.
(1994) and Clegg & Shafat (2010). Lastly Perrigue et al. (2009) found carbohydrates to be less
satiating than HFi.
Fiber & satiety
Two studies investigated high fiber meals effect on satiety; therefore this thesis has insufficient
studies, in order to conclude on the effect of fiber and satiety. However the studies included can
somewhat show a tendency of high fiber meals effect on satiety.
Kristensen et al. (2010) compared a HFi meal with HP meals. No differences were
found between the HFi test meal and the HP test meals within hunger. Similar results were found
for fullness and the SM intake. Comparable results were found, in the study by Holt, Brand-Miller,
& Stitt (2001), when comparing breads with different fiber contents. The results by Kristensen et al.
38
(2010) indicates that HFi and HP have the same effect on satiety, moreover it suggests that there is
a correlation between hunger, fullness and SM intake.
Perrigue et al. (2009) tested two HFi meals effect on satiety: LF/HFi and
LF/HP/LC/HFi. Likewise Kristensen et al. (2010), Perrigue et al. (2009) found no difference
between the ratings of hunger, after the HFi test meals and the LF/HP/LC test meal. Moreover they
found no difference between the hunger ratings after the HFi test meals and the LF or between the
HFi test meals. Lastly the LF/LP/HC test meal resulted in higher hunger ratings than the two HFi
test meals (p<0.05). This difference in hunger ratings may be due to the digestion process of fibers,
as it does not begin before it reaches the large intestine, thereby extending the process. The results
for fullness were somewhat similar to those of hunger, however in contrast to Kristensen et al.
(2010) the fiber test meals were found to result in a higher rating of fullness compared to the
LF/HP/LC test meal (p<0.05). Several factors could be the reason for the discrepancy. First
Perrigue et al. (2009) serves liquid foods whereas, Kristensen et al. (2010) serves solid foods,
resulting in a faster gastric emptying process, as the liquids are not effected by the lag phase.
Hereby only the liquids are emptied at approximately the same rate, as the nutrient content is
similar; thereby only the liquids containing fiber are affected by the body’s inability to digest fibers.
Secondly the fat content might have an influence as Perrigue et al. (2009) test meals contained a
lower fat content compared to Kristensen et al. (2010). Thirdly the calorie content might have a
impact on fullness, as Perrigue et al. (2009) HP test meal contained fewer kcal than the HFi test
meals, whereas the calorie content were constant in Kristensen et al. (2010) test meals. Lastly no
difference was found between the different test meals and the SM intake, indicating that the
satiating effect only occur within a 2-hour range. Overall the results by Perrigue et al. (2009)
suggest that there is no difference on satiety between HP and HFi meals, moreover the HFi results
in higher satiety compared to HC test meals.
Macronutrients & satiety
The literature showed a tendency for protein to be more satiating than fat and carbohydrate, where
carbohydrate was superior to fat. In addition it would seem that fiber was more effective than
carbohydrate in inducing satiety. The reasons for this effect are complex and remain to be explored;
several factors may be of influence, both physiological and psychological. Even though it would
seem that calorie content of a meal is of weak influence in regards to satiety, energy density may
still be a factor that could be of influence to the outcome (Poppitt et al., 1998). The digestion, rates
39
of pre-absorptive and post-absorptive mechanisms of fat, protein, carbohydrate and fiber may also
be a considerable factor, as it differs considerably and could cause the different short-term satiety
effects (Fischer et al., 2004). Furthermore subjective opinions on palatability caused by sensory
properties such as: feel, viscosity, touch, taste and moisture may explain the conflicting results
within the studies, as palatability previously has been found to affect energy intake. This is seen in
the studies by Dougkas & Ostman (2016), Rolls et al. (1991), Rolls et al. (1988) and Rolls et al.
(1988). Such a hypothesis is supported by Buckland et al. (2015), who found subjective opines on
satiety of different foods. Lastly diet induced thermogenesis has been associated with satiety
(Westerterp-Plantenga et al., 1997). There is indicative evidence towards diet induced
thermogenesis having an effect on satiety scores; the higher the diet-induced thermogenesis is, the
more satiating a meal is. In this context full fat meals have the lowest diet induced thermogenesis
compared to protein as the highest (Crovetti, Porrini, Santangelo, & Testolin, 1998). Protein has in
previous research proved to be more satiating than the other macronutrients, thereby limiting the
energy intake after a meal, while also increasing thermogenesis; influencing satiety and energy
expenditure (Paddon-Jones et al., 2008).
An important factor to consider is the different procedures implemented in the studies,
more specifically at what time the different parameters such as hunger were measured. Time seems
to be of the essence, concerning satiety and its related factors. The studies by Fallaize et al. (2013),
Cotton et al. (1994) and Clegg & Shafat (2010), who measured on whole day satiety found no
difference on satiety parameters, suggesting that satiety is limited to a short time frame; <7-10
hours. In addition differences between satiety measures were limited to ratings prior to the ad
libitum meal, similarly suggesting that the SM overwrites the effect of a previous meal. This
proposes that to obtain the full effect of macronutrient induced satiety, one would be recommended
to follow the same effective macronutrient composition throughout the day. Cotton et al. (1994) and
Fischer et al. (2004) found a significant difference on hunger ratings following the test meals, yet
no effect in the SM intake. A reason for the given outcome may be due to the extended time
between a test meal and the SM, suggesting that satiety only affects subsequent intake within a ≤3-4
hour period. Perrigue et al. (2009) was the only study, which found a difference on hunger, but not
on SM intake within a <3-hour period; this was likely due to the meal type presented in the study.
Studies including a protocol concerning a 3-hour period, found a significant difference on hunger
ratings and SM intake; supporting the findings from Cotton et al. (1994) and Fischer et al. (2004),
that the effect of satiety occurs within a 3-hour timeframe.
40
5.1 Literature considerations
The limitations and strength of the included studies needs to be taking into consideration in order to
evaluate the results of this thesis. It is important to recognize that it can be difficult to conduct
research on the control of energy intake, as it is both expensive and complicated to measure habitual
intake (Geissler & Powers, 2005, p. 96). Something to remember is therefore that all the included
studies tested short-term satiety parameters, which means that the outcome they found may not be
of relevance for long-term interventions. This would have to be investigated in studies to come.
All the included studies are randomized control trials (RCT), which has the strength of
avoiding selection bias (Carneiro & Howard, 2011, p. 122), moreover RCT is rated among the
highest in the evidence hierarchy (Kjøller et al., 2007, p. 371). Two different trial designs are used
in the included studies; crossover and factorial trials. Furthermore all the included studies
implemented crossover designs, where the subjects' acts as it own control (Thelle, 2015, p. 131).
Benefits of using own control, in studies dealing with satiety, are that the rating of satiety is
subjective. Therefore by using the control of the subjects rating of hunger, at a fasting phase, will
reduce possible bias, as it reflects the subject’s satiety ratings on the specific test day. Crossover
trials are appropriate for short-term studies, as the subjects have a washout period between each test
meal. This enables to control for confounders and make alterations (Carneiro & Howard, 2011, p.
124). Cotton et al. (1994), Dougkas & Ostman (2016) and Perrigue et al. (2009) also included a
factorial design, where the results are both compared with the subjects own control and a control
meal (Thelle, 2015, p. 131). This design has the benefit of assessing interactions between the test
meals and the subjects own control, thereby evaluating on various interventions at once, which
saves time and money (Carneiro & Howard, 2011, p. 123). Lastly all the studies, except the one by
Kristensen et al. (2010), are single-blinded. This has the strength of limiting information bias from
the subjects in the study (Carneiro & Howard, 2011, p. 127). The study design could have been
even stronger if double-blinding was used, hereby the information bias from the observer also could
have been reduced (Ibid). Kristensen et al (2010) uses an open-labeled study, which should be
taking into consideration when evaluating the results.
In relation to study design, an important component is the number of included
participants. This is an important factor, which can determine the outcome of a study; studies with
insufficient power may fail to find any effect on the different treatments (Flint et al., 2000). Our
thesis included studies with as few as 9 participants (Clegg & Shafat, 2010) to as many as 40
(Perrigue et al., 2009); the statistical power of the different studies is therefore of relative variation.
41
However this limitation can be difficult to avoid, due to the extent of work required for these types
of studies. In addition some of the included literature did experience dropouts due to: poor
compliance, being unable to attend study days, personal reasons, protocol non-adherence, logistic
problems and dislike of the ad libitum meal. Dropouts were limited to 5 studies; varying from 3%
dropout (Fallaize et al., 2013) to 20% (Kristensen et al., 2010).
In regards to participants, few studies took gender differences into account. This is an
issue that must be considered, as there may be differences between the sexes on satiety regulation,
for example in relation to portion size (Perrigue et al., 2009). As men are of larger body size and
energy needs, they would require larger portions to experience the same rate of satiety. If not taken
into account, within the different studies, this factor could result in large variation, thereby hiding
the real effect (Dougkas & Ostman, 2016).
Evaluating the rating scales and thereby the measurements, several factors must be
considered. First of all, one should keep in mind that the measurements are subjective; therefore the
subjects might interpret the feeling of hunger and fullness differently. However the subjects act as
their own control, thereby minimizing possible bias from the different interpretations. Secondly,
different study parameter must be considered, as the included subjects might alter the results or
require different study designs, such as prior diet standardization (Flint et al., 2000). The included
studies by Dougkas & Ostman (2016), Fischer et al. (2004), Perrigue et al. (2009), and Poppitt et al.
(1998) uses prior diet standardization, in order to reduce possible bias on the rating of satiety.
However the fact that the other studies do not include prior diet standardization should not be
viewed as a limitation, due to the fact that it does not seem to affect VAS ratings (Flint et al., 2000).
Other factors that have been shown to affect the ratings are age, gender, and physical activity
(Gregersen et al., 2011). These influencing factors are all taken into consideration, in order to
minimize possible bias. All the studies subjects are within the same age range of 20-30 years,
thereby not affected by the age influence on satiety ratings (Ibid), making the included studies
comparable. The different satiety ratings between genders, are likely due to hormonal differences
(Ibid), thus it is difficult to take into account, when planning the procedure of the study. Dougkas &
Ostman (2016) and Rolls et al. (1991) made alterations in the test meals calorie content and
quantity, in order to make up for the gender differences. Furthermore all the included studies
instructed the subjects to refrain from strenuous physical activity the day before the test, to avoid
alterations in the results. A third factor affecting the results is the subject’s perception of a meal’s
satiety. Previous studies have found that the foods energy density, fiber content, macronutrient
42
composition and perceived healthiness are associated with the perceived satiety (Buckland et al.,
2015). As the subjects included in the studies are able to see the food they consume, it cannot be
overruled that the ratings of satiety are influenced by the perceived satiety, combined with the
satiety effect from the food consumed.
There are several limitations considering the protocols of the included studies, which
in some way or another not only limit the comparability between the different studies, but also
between the different test meals. Within this consideration there are three primary factors, which
differ between test meals and seems to have an influence on satiety; quantity/portion size, test meal
structure and meal type. Portion size seems to be a primary factor influencing satiety (Kral, 2006).
Some studies compare test meals with up to a 6 times difference in quantity (Rolls et al., 1988), this
makes it difficult to determine whether the macronutrient composition or the quantity is the cause
for the given effect. Other test meals are presented in liquid form, while most are served as solid
foods. There is however suggestive evidence for the test meal structure having an influence on
satiety ratings (Dougkas & Ostman, 2016), which can limit comparison between different test
meals. Last but not least, the test meals did come in different meal types, as in the study by Rolls et
al. (1988), where for example chicken and pasta were served, which many would consider as a
dinner and turkish delight and confectionery, which is often presented as snacks or dessert. The
attribute of not presenting typical breakfast foods, may influence the subjective perception of a test
meals satiety value and thereby affecting the results (Dougkas & Ostman, 2016). These limitations
must be taken into consideration when viewing the results of the included studies, as there are
several confounding factors, which hinder clear conclusions.
There seems to be a lack of mentioning clinical significance. Statistical significance is
of high importance, in order to see if the findings are caused by chance or due to treatment (Valanis,
1999, p. 363). Statistical significance does however not necessarily speak for the clinical
significance: whether or not the outcome is of real importance in treatment. The statistically
significant effect may not be big enough for the treatment to have an actual clinical effect, which
could influence a given outcome (Ibid). For example a high protein test meal compared to a high fat
test meal might score a p-value of 0.05 on SM intake, which would be deemed as statistically
significant. The clinical difference might however be less significant, if there was<10 calories
between the test meals. This would most likely not have an impact on weight control, and would
therefore not be considered clinically important.
43
6. Conclusion
The association between macronutrients and their effect of satiety was inconclusive, as further
influencing factors were established. Quantity/portion size, meal type and sensory cues all seemed
to play an important role in the rating of satiety. The influence of these aspects needs more research
in order to examine their contribution to satiety. However this thesis found suggestive evidence for
fat to affect satiety to a lesser extent than both carbohydrate and protein, thereby it seems that high
fat meals increase energy intake. In addition protein seems to increase fullness while decreasing
hunger and subsequent meal intake, due to its increased satiating effect. Carbohydrates effect on
satiety is inconsistent, however a weak tendency points toward carbohydrates being more satisfying
than fat and less satisfying compared to protein. Lastly the effect of fiber seems to result in a higher
satiety compared to carbohydrates. The reason for the given outcome is still not known and may be
caused by both physiological and psychological factors.
7. Perspectives
This thesis investigated how macronutrients invoke satiety and to what degree. We found
suggestive evidence for how to compose the macronutrient composition of a meal, in order to
increase satiety and limit subsequent intake. This information may provide an effective tool for
future counseling and become of great value in the fight against obesity. In the examination, this
thesis came across several factors that may have an influence on satiety. Therefore more research is
required, in order to understand satiety and make it a useable tool in fighting overweight and
obesity.
The subjective perception of different foods and their satiating abilities was found to
be an interesting factor that may influence satiety. Buckland et al. (2015) supports this hypothesis,
as their results of perceived satiety of foods, showed the perceptions of food to be of influence. To
what extend and why perceived satiety influences satiety ratings, is to our knowledge unknown.
More research is therefore needed in this area, as it may be of significant importance in relation to
satiety. Earlier studies have previously investigated satiety in regards to a specific value (SI%). Holt
et al. (1995) found foods to be an important factor, when investigating satiety, as foods within
different macronutrient groups, differ in their satiety score. It would therefore be of great value to
investigate, which foods have the greatest satiety rate and combine it within the macronutrient
composition of a meal. It is important to chain the foods with the macronutrients composition, as
44
single foods cannot ensure overall health; the whole diet need to taken into consideration (Nordic
Council of Ministers, 2008, p. 21). The quantity was also found to be an influencing factor in this
thesis; therefore we recommend future studies to investigate the portions size effect on energy
intake, as this angle could be essential in relation to satiety, when fighting weight problems.
In general there is still many relations and questions that may be worth investigating,
when looking at satiety. The successful treatment of obesity and weight gain may very well depend
on research to come.
8. Practice considerations
Every year, a substantial amount of people deal with overweight and weight gain, this tendency
causes millions of deaths (WHO, 2014, p. 79). There are clear indications for the primary causes,
providing this tendency, being increased food intake, lack of physical activity and an abundance of
food availability (Aljuraiban et al., 2015). However when we know the reason for the given
problem, how are we not able to fix it? Weight gain and weight control is a much more complex
and thorny subject, than what most people believe it to be. The problem is not only influenced by
physiological elements, but also psychological; this combination makes it extremely difficult to lose
weight after it has been gained (Byrd-Bredbenner et al., 2012, pp. 342–342). In line with the
increasing knowledge availability in the society, the general population finds it more difficult to
distinguish between right and wrong. This has resulted in people trying different diets, often with no
support of scientific evidence. Instead people choose diets recommended by friends, families or
celebrities, who has had a positive experience with the diet; FAD diets has become relatively
popular, yet they rarely provide any long-term success (Byrd-Bredbenner et al., 2012, pp. 338–341).
But instead of focusing on how to resolve the problem, it might be beneficial to know how to
prevent it in the first place. It would seem that one of the primary causes, for causing weight gain, is
increased food intake. A relevant question would therefore be; how can we effectively limit this
tendency? A perspective could be through satiety: by increasing the satiety of our habitual diets, we
may be influenced to eat less.
It is important for our profession to continue research in the field of health, thus we may be able to
find evidence based and effective solutions to the problems of our modern society. Through our
thesis we investigated satiety and more specifically how it might be influenced by the different
45
macronutrients. We found suggestive evidence for increasing satiety within a meal, by increasing
protein and fiber content while decreasing fat. With the given finds, we may be able to implement a
whole day diet consisting of the stated macronutrient composition that could increase satiety and
limit subsequent intake throughout the day. With this tool, we may provide clients, as well as the
population, an effective way of controlling their weight and thereby avoiding weight gain in the
first place. In addition such a diet tool may increase adherence for people trying to loose weight,
through a restricted diet. This new information may help us, as health professionals, to guide our
clients to a better and healthier life.
46
9. List of reference
Aljuraiban, G. S., Chan, Q., Oude Griep, L. M., Brown, I. J., Daviglus, M. L., Stamler, J., … Frost,
G. S. (2015). The Impact of Eating Frequency and Time of Intake on Nutrient Quality and Body
Mass Index: The INTERMAP Study, a Population-Based Study. Journal of the Academy of
Nutrition and Dietetics, 115(4), 528–536.
Aller, E. E. J. G., Larsen, T. M., Claus, H., Lindroos, A. K., Kafatos, A., Pfeiffer, A., … van Baak,
M. A. (2014). Weight loss maintenance in overweight subjects on ad libitum diets with high or low
protein content and glycemic index: the DIOGENES trial 12-month results. International Journal of
Obesity, 38(12), 1511–1517.
Astrup, A., Bügel, S., dyerberg, J., & Sten, S. (Eds.). (2015). Menneskets ernæring (4th ed.). Kbh.:
Munksgaard.
Blundell, J. E., & Burley, V. J. (1987). Satiation, satiety and the action of fibre on food intake.
International Journal of Obesity, 11(1), 1–92.
Buckland, N. J., James Stubbs, R., & Finlayson, G. (2015). Towards a satiety map of common
foods: Associations between perceived satiety value of 100 foods and their objective and subjective
attributes. Physiology & Behavior, 152, 340–346.
Byrd-Bredbenner, C., Moe, G., Beshgetoor, D., & Berning, J. (2012). Wardlaw’s perspectives in
nutrition. (9th ed.). New York; London: McGraw-Hill Higher Education.
Carneiro, I., & Howard, N. (2011). Introduction to Epidemiology (Second edition). Maidenhead:
Open University Press.
Clegg, M., & Shafat, A. (2010). Energy and macronutrient composition of breakfast affect gastric
emptying of lunch and subsequent food intake, satiety and satiation. Appetite, 54(3), 517–523.
Cotton, J. R., Burley, V. J., Weststrate, J. A., & Blundell, J. E. (1994). Dietary fat and appetite:
similarities and differences in the satiating effect of meals supplemented with either fat or
carbohydrate. Journal of Human Nutrition and Dietetics, 7, 11–24.
Crovetti, R., Porrini, M., Santangelo, A., & Testolin, G. (1998). The influence of thermic effect of
food on satiety. European Journal of Clinical Nutrition, 52, 482–488.
Dougkas, A., & Ostman, E. (2016). Protein-Enriched Liquid Preloads Varying in Macronutrient
Content Modulate Appetite and Appetite-Regulating Hormones in Healthy Adults. Journal of
Nutrition, 146(3), 637–645.
Evans, D. (2003). Hierarchy of evidence: a framework for ranking evidence evaluating healthcare
interventions. Journal of Clinical Nursing, 12(1), 77–84.
Fallaize, R., Wilson, L., Gray, J., Morgan, L. M., & Griffin, B. A. (2013). Variation in the effects of
three different breakfast meals on subjective satiety and subsequent intake of energy at lunch and
evening meal. European Journal of Nutrition, 52, 1353–1359.
Fischer, K., Colombani, P. C., & Wenk, C. (2004). Metabolic and cognitive coefficients in the
development of hunger sensations after pure macronutrient ingestion in the morning. Appetite,
42(1), 49–61.
Flint, A., Raben, A., Blundell, J. E., & Astrup, A. (2000). Reproducibility, power and validity of
visual analogue scales in assesment of appetite sensations in single test meal studies. International
Journal of Obesity, 24, 38–48.
Fogelholm, M., Anderssen, S., Gunnarsdottir, I., & Lahti-Koski, M. (2012). Dietary macronutrients
and food consumption as determinants of long-term weight change in adult populations: a
systematic literature review. Food & Nutrition Research, 56(0).
Geissler, C., & Powers, H. J. (Eds.). (2005). Human nutrition (11th ed). Edinburgh ; New York:
Elsevier/Churchill Livingstone.
Gerstein, D. E., Woodward-Lopez, G., Evans, A. E., Kelsey, K., & Drewnowski, A. (2004).
Clarifying concepts about macronutrients’ effects on satiation and satiety. Journal of the American
Dietetic Association, 104(7), 1151–1153.
Gregersen, N. T., Møller, B. K., Raben, A., Kristensen, S. T., Holm, L., Flint, A., & Astrup, A.
(2011). Determinants of appetite ratings: the role of age, gender, BMI, physical activity, smoking
habits, and diet/weight concern. Food & Nutrition Research, 55(00).
Halton, T. L., & Hu, F. B. (2004). The Effects of High Protein Diets on Thermogenesis, Satiety and
Weight Loss: A Critical Review. Journal of the American College of Nutrition, 23(5), 373–385.
Hjørland, B. (2011). Evidence-based practice: An analysis based on the philosophy of science.
Journal of the American Society for Information Science and Technology, 62(7), 1301–1310.
Holm, A. B. (2013). Philosophy of science: an introduction for future knowledge workers.
Frederiksberg C: Samfundslitteratur.
Holt, S., Brand Miller, J., Petocz, P., & Farmakalidis, E. (1995). A satiety index of common foods.
European Journal of Clinical Nutrition, 49, 675–690.
Holt, S. H. A., Brand-Miller, J. C., & Stitt, P. A. (2001). The effects pf equal-energy protions of
different breads on blood glucose levels, feelings of fullness and subesequent food intake. Journal
of the American Dietetic Association, 101, 767–773.
Kjøller, M., Juel, K., & Kamper-Jørgen, F. (Eds.). (2007). Folkesundhedsrapporten Danmark 2007
(2. opl). København: Statens Institut for Folkesundhed.
Kral, T. V. E. (2006). Effects on hunger and satiety, perceived portion size and pleasantness of taste
of varying the portion size of foods: A brief review of selected studies. Appetite, 46(1), 103–105.
Kristensen, M., Jensen, M. G., Riboldi, G., Petronio, M., Bügel, S., Toubro, S., … Astrup, A.
(2010). Wholegrain vs. refined wheat bread and pasta. Effect on postprandial glycemia, appetite,
and subsequent ad libitum energy intake in young healthy adults. Appetite, 54(1), 163–169.
Larsen, T. M., Dalskov, S.-M., van Baak, M., Jebb, S. A., Papadaki, A., Pfeiffer, A. F., … Astrup,
A. (2010). Diets with high or low protein content and glycemic index for weight-loss maintenance.
New England Journal of Medicine, 363(22), 2102–2113.
Layman, D. K., Evans, E. M., Erickson, D., Weber, J., Bagshaw, D., Griel, A., … Kris-Etherton, P.
(2009). A moderate-protein diet produces sustained weight loss and long-term changes in body
composition and blood lipids in obese adults. The Journal of Nutrition, 139(3), 514–521.
Longenbaker, S. N. (2014). Mader’s understanding human anatomy & physiology (8th ed.).
Murphy, K. G., & Bloom, S. R. (2006). Gut hormones and the regulation of energy homeostasis.
Nature, 444(7121), 854–859.
NCBI. (n.d.-a). Adult - MeSH - NCBI. Retrieved November 8, 2016, from
https://www.ncbi.nlm.nih.gov/mesh/68000328
NCBI. (n.d.-b). Satiation - MeSH - NCBI. Retrieved November 8, 2016, from
https://www.ncbi.nlm.nih.gov/mesh/?term=satiation
Nordic Council of Ministers, N. C. of M. (2008). Nordic Nutrition Recommendations 2012. Nordic
Nutrition Recommendations 2012, 5(11), 1–3.
Paddon-Jones, D., Westman, E., Mattes, R. D., Wolfe, R. R., Astrup, A., & Westerterp-Plantenga,
M. (2008). Protein, weight mangement, and satiety. American Journal of Clinical Nutrition, 87,
1558S–61S.
Perrigue, M. M., Monsivais, P., & Drewnowski, A. (2009). Added Soluble Fiber Enhances the
Satiating Power of Low-Energy-Density Liquid Yogurts. Journal of the American Dietetic
Association, 109(11), 1862–1868.
Poppitt, S. D., Mccormack, D., & Buffenstein, R. (1998). Short-term effects of Macronutrient
Preloads on Appetite and Energy Intake in Lean Women. Physiology & Behavior, 64(3), 279–285.
Rolls, B. J., Hetherington, M., & Burley, V. J. (1988). The specificity of satiety: the influence of
foods of different macronutrient content on the development of satiety. Physiology & Behavior, 43,
145–153.
Rolls, B. J., Kim, S., Mcnelis, A. L., Fischman, M. W., Foltin, R. W., & Moran, T. H. (1991). Time
course of effects of preloads high in fat or carbohydrate on food intake and hunger ratings in
humans. American Journal of Physiology, 4, 756–762.
Shils, M. E., Shike, M., Ross, A. C., Caballero, B., & Cousins, R. (Eds.). (2006). Modern nutrition
in health and disease (10th ed). Philadelphia: Lippincott Williams & Wilkins.
Thelle, D. (2015). Epidemiology: A basis for public health and disease prevention. Oslo:
Gyldendal.
Valanis, B. (1999). Epidemiology in health care (3rd ed). Stamford, Conn: Appleton & Lange.
Westerterp-Plantenga, M. S., Wijckmans-Duijsens, N. E., Verboeket-Van De Venne, W. P., De
Graaf, K., Weststrate, J. A., & Hof, K. H. V. H. (1997). Diet-induced thermogenesis and satiety in
humans after full-fat and reduced-fat meals. Physiology & Behavior, 61(2), 343–349.
WHO. (2014). Global status report on noncommunicable diseases 2014: attaining the nine global
noncommunicable diseases targets; a shared responsibility. Geneva: World Health Organization.