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Web Review - Chapter 16 – pg. 1
Concepts of Fitness and Wellness / Concepts of Physical Fitness
Web Review - Concept 16
Nutrition
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Web Review - Chapter 16 – pg. 2
Web16-1:
Understanding Differences in Nutritional Guidelines (p. 308)
The government uses a variety of different nutritional guidelines to provide recommendations to
the public. Many people use these guidelines interchangeably but there are some differences in
the intent and scope in some of the guidelines. A brief description of each of the guidelines is
provided below.
RDA:
The National Research Council's Recommended Dietary Allowances (RDA) is the standard for
the daily nutritional needs of healthy people. Broken down by gender and age, it covers 25
vitamins, minerals, and trace elements that are critical for a healthy diet. RDA's are neither the
absolute minimum, maximum, or ideal amount of a nutrient you should consume; they merely
provide an amount that you can be sure is safe and will promote proper health and development.
The RDA’s are set by the Food, and Nutritional Board of the National Academy of
Sciences/National Research Council.
U.S. RDA:
The FDA established the U.S. Recommended Daily Allowance (USRDA) in 1973 as a simplified
daily nutritional requirement standard for food labeling. Because of confusion between the terms
USRDA and RDA, the term USRDA has been renamed RDI.
RDI:
The FDA established the Reference Daily Intake (RDI) to replace the term USRDA (see above)
due to confusion between the terms USRDA and RDA. The RDA also adds six new nutrients,
Vitamin K, Selenium, Chloride, Manganese, Chromium, and Molybdenum.
DRV:
The Daily Recommended Values (DRV) are established for special components of foods not
listed by the RDI's, such as Fat, Cholesterol, Carbohydrates, and Protein. Unlike other daily
nutritional requirements, the DRV's are derived from how many calories a day you need.
Web Review - Chapter 16 – pg. 3
Concepts of Fitness and Wellness / Concepts of Physical Fitness
Web16-2: Estimating Energy Expenditure (p. 311)
Daily energy expenditure is made up of the basal energy requirements that are needed for daily
living as well as the amount of energy expended during physical activity. An additional
component, known as the thermic effect of food, reflects the energy required for the processing
and metabolism of food. This component is thought to comprise about 10% of a person’s daily
energy expenditure.
There are various methods that are available to assess energy expenditure. Self-report
instruments are the most commonly used since they can be conducted on large numbers of
people in a cost effective manner. The self-report instrument used in lab 15-C requires an
individual to keep a fairly detailed log over the course of the day. This provides a fairly precise
measure of energy expenditure. It is also possible to assess energy expenditure more crudely
with other self-report procedures.
One simple procedure is to estimate basal metabolic rate and add on an estimate of calories
expended in physical activity. Follow the steps below to estimate your daily energy expenditure.
Step 1: BMR (kcal)
=
10
x
______
Wt. (lbs)
=
_____ kcal
Step 2: PA (kcal)
=
______
BMR(step 1)
x
_______
PA level *
=
_____ kcal
=
_____ kcal
Estimate your activity level and use the following values in the calculation:
Inactive = .30
Moderately active = .50
Vigorously active = .80
Step 3: Total EE (kcal)
=
___________
BMR (step 1)
+
_________
PA (step 2)
This calculation can provide only a rough approximation of a person’s energy expenditure. Basal
metabolic rate (step 1) will depend largely on body size since larger people will require more
energy at rest. The contribution from physical activity will vary by a person’s activity status.
This is expressed here as a multiple of a person’s BMR since larger people will expend more
calories for a given level of physical activity. The sum of these two effects provides an estimate
of energy expenditure. The results can only reflect a “typical” energy expenditure value as your
activity level is likely to vary considerably from day to day.
Web Review - Chapter 16 – pg. 4
Concepts of Fitness and Wellness / Concepts of Physical Fitness
Web16-3: A Comparison of Dietary Fats (p. 311)
Fat is one of the three main nutrients that supply energy to the body. The other two are
carbohydrates, and proteins. Fats are made up of hydrocarbon chains (chains of carbon and
hydrogen) of varying lengths. Fats vary in the exact arrangement of carbon and hydrogen on the
molecule and in the overall length of the chain. A fat is considered saturated if all of the
available carbon molecules have hydrogen on them. This chemical structure causes saturated fats
to be solids at room temperature. Saturated fat comes mainly from animal sources, like meat,
butter, and milk. A fat is considered unsaturated if it has one (mono-) or more (poly-) carboncarbon “double bonds”. This double bond changes the chemical properties and causes these fats
to be liquids at room temperature. Unsaturated fats are typically from vegetable sources and
inlclude the fats found in corn, safflower, soybean, and sunflower oils, for example. There is
also the type of fat (Omega-3 fatty acids) found in many higher-fat seafoods such as mackerel,
and salmon. The chemical structures of a saturated and unsaturated fat are presented below for
comparison.
H HHHH H HHHH H HHHH0
HC- C- C-C-C-C-C-C-C-C- C-C-C-C-C-C-OH
H HHHH HHHHH H HHHH
Palmitic Acid - a saturated fat
H HHHH H HH
HH H HHHH 0
HC-C- C-C-C-C-C-C-C= C-C-C--C-C-C-C-C-C-OH
H HHHH HHHH H HH H HHHH
Oleic Acid - an unsaturated fat
While the two compounds look very similar, the chemical properties and metabolic effects of
these fats are very different. Saturated fats are known to be atherogenic, meaning they have a
tendency to promote atherosclerosis (the buildup of fatty plaque on the walls of the arteries).
Unsaturated fats, on the other hand, do not raise cholesterol or promote atherosclerosis. Mono-
Concepts of Fitness and Wellness / Concepts of Physical Fitness
Web Review - Chapter 16 – pg. 5
unsaturated fats (which have only 1 double bond) such as olive oil, canola oil have been found to
lower cholesterol and have beneficial effects on lipid profiles. The same beneficial effect is
found for the omega-3 fatty acids in seafood.
There has been considerable interest in recent years in a type of fat known as a “trans-fatty acid”
which have been found to be highly atherogenic. This type of fatty acid is created when an
unsaturated fat (e.g. an oil) is converted into a saturated one in the process of hydrogenation. The
hydrogenation process extends the shelf life of products and makes the fat more solid at room
temperature. For example, this is how vegetable oils are converted into margarine that can be
more conveniently spread onto foods. To complete the hydrogenation process, hydrogen is
bubbled into the oil until the hydrogen molecules bond to the “free” carbon molecules. The
resulting compound becomes a saturated fat known as a “trans” fatty acid because the chemical
bond is different than in other fats. From a dietary standpoint, foods that are hydrogenated may
be as harmful as saturated fats.
Web Review - Chapter 16 – pg. 6
Concepts of Fitness and Wellness / Concepts of Physical Fitness
Web16-4: Composition of Oils (p. 313)
Because oils are liquids at room temperature many people assume that they are completely
unsaturated. A closer look reveals that not all oils are created equal. Oils vary considerably in the
percentage of saturated, poly-unsaturated and mono-unsaturated fats that they contain.
Type
Saturated
Polyunsaturated.
Monounsaturated
Safflower
9
75
16
Sunflower
10
66
24
Corn
13
59
28
Soybean
14
58
28
Sesame
14
42
44
Peanut
17
32
51
Palm
49
9
42
Olive
14
8
78
7
35
58
Canola
Note: values reflect percentages of each type of fat.
In selecting oils, it is best to choose oils that are high in mono-unsaturated fats and low in
saturated fats. Good choices for the kitchen are olive oil and canola oil since they have the larger
percentage of mono-unsaturated fats. This type of fat has actually been shown to be good for
health since it can actually lower blood levels of LDL cholesterol.
Concepts of Fitness and Wellness / Concepts of Physical Fitness
Web Review - Chapter 16 – pg. 7
Web16-5: Comparing Simple and Complex Carbohydrates (p.
314)
Carbohydrates are the body’s primary source of energy. There are two types of carbohydrates
(simple and complex). They each are composed of the same three elements (carbon, hydrogen,
and oxygen) - these are also the same components that also make up dietary fat – but they have
different functions and properties in the body.
Simple Carbohydrates:
Simple carbohydrates are made up of individual sugar molecules (shown as a G for glucose).
They are found in candy, soda, fruit and other sweet food. The molecules can be made up of
either one (monosaccharide) or two (disaccharide) sugar units. Three types of monosaccharides
are: fructose, glucose, and galactose.
Complex Carbohydrates:
Complex carbohydrate molecules are made up of longer chains of sugar units or simple sugars.
They are often called polysaccharides, which simply means many saccharides. Complex
carbohydrates are found in starchy foods such as potatoes, rice, pasta and bread as well as
vegetables. Complex carbohydrates also contain dietary fiber.
Puzzling Questions about Carbohydrates:
1. If starches are sugars then why don’t they taste sweet?
The difference in taste is due to the length or size of the molecule. Complex carbohydrates are
large molecules and they simply do not fit on the receptors of the taste buds on the tongue. As a
polysacchride dissolves and is broken down by digestive enzymes in the mouth the molecules
become smaller and start to taste sweeter.
2. Why are complex carbohydrates considered as “good foods” while simple sugars are
considered “bad foods”?
Complex carbohydrates and simple carbohydrates are basically made up of the same chemical
components (sugar units or sacharide molecules). Despite these similarities, they are processed
and used very differently within the body. Because simple sugars are made up of individual units
they cause large increases in blood sugar which causes the body to release the hormone insulin.
Insulin causes the sugars to be taken up and tends to promote the deposition of fat. Because
complex carbohydrates have to be broken down one at a time, they do not cause a large increase
in insulin. They therefore do not get stored as readily as simple sugars do. The excessive
fluctuations in blood glucose levels caused by consumption of simple sugars can also lead to
Concepts of Fitness and Wellness / Concepts of Physical Fitness
Web Review - Chapter 16 – pg. 8
decreases in insulin sensitivity and an increased risk for Type 2 diabetes. In addition to these
differences, complex carbohydrates tend to contain other nutrients such as vitamins and minerals
as well as dietary fiber while simple carbohydrates tend to have little nutritional value. Thus,
while the two compounds look alike they have very different effects on the body.
3. If fruit is considered a simple carbohydrate why is fruit considered to be healthy but
other simple sugars are not?
The sugars in fruit are composed of fructose molecules instead of glucose. Fructose does not
cause increases in blood sugar and therefore doesn’t lead to any of the metabolic imbalances that
are associated with simple sugars (see question 2). Fruit also is packed with vitamins, minerals
and fiber while most simple sugar foods are just “empty calories”.
Concepts of Fitness and Wellness / Concepts of Physical Fitness
Web Review - Chapter 16 – pg. 9
Web16-6: Carbohydrate Loading (p. 321)
Carbohydrates are the bodies preferred source of energy during exercise. The body has only a
limited supply of glucose available in the bloodstream. During exercise, the surge of adrenaline
causes the hormone glucagons to be released. This hormone allows the body to break down some
of its stored sugar (stored as a compound called glycogen) and release it into the blood so it can
be used by the exercising muscles. The body has a limited supply of glycogen (about 2000 kcal).
If exercise is performed for long periods of time such as marathon running the supply of
glycogen gets pretty low. When the supply gets to a critically low level, the body begins to
restrict the release of glycogen in order to save glucose for the brain. This forces the body to
begin having to use other energy sources (primarily fat) to contribute to the production of energy.
While fat provides a good source of energy during aerobic exercise, it is harder for the body to
produce the energy as quickly as it is needed and the person must usually slow down. This
metabolic state is typically called “hitting the wall” because you feel quite sluggish and tired
without the same supply of available glucose. Once the fat metabolism catches up the body can
continue exercising more vigorously.
To avoid hitting the wall, many endurance athletes try to maximize their level of stored fuel
(glycogen) prior to racing or competing in a major endurance activity. An early study by
Bergstrom in 1967 demonstrated that the formation of glycogen is enhanced following a diet
high in carbohydrate. He also observed that endurance time is greater among the athletes
consuming a higher carbohydrate diet. The practice of consuming a higher percentage of
carbohydrates in the diet became known as “carbohydrate loading”. It is important to point out
that the key to carbohydrate loading is not necessarily to eat more food but to eat a good sized
meal that is comprised mainly of carbohydrates. Individuals interested in further information on
carbohydrate loading are advised to consult a registered dietician (RD).
Concepts of Fitness and Wellness / Concepts of Physical Fitness
Web Review - Chapter 16 – pg. 10
Web16-7: Supplemental Readings (p. 325)
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the American Dietetics Association, 97, 1317-1321, 1997.
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
Babbitt D. “Training Theory: Periodization.” American Track and Field. (1998), Summer.
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
Burney, M. W. & B. A. Brehm. The Female Athlete Triad. Journal of Physical Education Recreation and
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