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FA CT S H E ET
Sugar in the diet of sports people
The right diet is as important as the right amount of training for all
sports people. There are benefits to be gained from paying
attention to food and fluid intake, for both the serious athlete and
those who participate in casual exercise. Diet and nutrition could
significantly improve progress, performance and enjoyment during
training and competition. Correct nutrition could also reduce the
risk of injuries, fatigue and susceptibility to illness.
Dietary carbohydrates provide the major energy source in the diet
of most people. For sports people, attention to both the quantity
and quality of the carbohydrate in the diet can be particularly
important. Carbohydrates are provided by a diverse range of
foods and drinks and there is no universal system that can
adequately describe the diverse metabolic, functional and
nutritional features of these various carbohydrate containing
foods. Athletes are encouraged by peak sports and nutrition
organisations to choose carbohydrate-rich foods and drinks that
meet their specific needs in regards to nutrient-density, glycaemic
index, eating appeal and practicality according to the
requirements of each sporting situation.1
This fact sheet provides an overview of the role of sugars in the
diet of sports people. The dietary needs of individuals vary
enormously and this is particularly so with sportspeople. The food
and nutrition requirements of an endurance athlete who runs
marathons will be quite different to the needs of someone who
plays a high intensity sport, such as rugby.
If you are very serious about your sport, or are simply feeling that
you don’t have the energy you need to really enjoy it, you could
benefit from one-to-one advice from a qualified health professional
such as a sports dietitian. However, there are some basic
principles that could apply to everyone and these principles are
outlined in this fact sheet.
This information summarises recommendations from peak
sports and nutrition organisations. For more information you may
wish to contact these organisations directly; Australian Institute of
Sport (www.ais.org.au), High Performance Sport New Zealand
(www.hpsnz.org.nz), Dietitians Association of Australia
(www.daa.asn.au) and Dietitians New Zealand (www.dietitians.org.nz).
Where does sugar fit in the diet?
Carbohydrates, including sugars, are a fuel source for the muscles and central nervous system.2 The availability of carbohydrate can play a key
role in exercise performance, therefore, many sports nutrition guidelines promote carbohydrate intake before, sometimes during and after
exercise to meet the fuel requirements of the activity.2, 3
CONTINUED OVER
ACUTE FUELLING
STRATEGIES
DAILY NEEDS FOR
FUEL AND RECOVERY
TABLE 1: RECOMMENDED CARBOHYDRATE INTAKES2
SITUATION
RECOMMENDED CARBOHYDRATE INTAKE
Low-intensity or skill-based activities
3-5 g/kg body weight
Moderate exercise for ~1 hr/day
5-7 g/kg body weight
Moderate to high intensity exercise for 1-3 hrs/day
6-10 g/kg body weight
Moderate to high intensity exercise for >4-5 hrs/day
8-12 g/kg body weight
Preparation for events <1.5 hrs
7-12 g/kg body weight per 24 hrs (as per daily fuel needs)
Carbohydrate loading in preparation for events
>1.5 hrs of sustained/intermittent exercise
1-4 g/kg body weight (consumed 1-4 hrs pre-competition)
During brief exercise (<45 min)
Not required
During sustained high-intensity exercise (45-75 min)
Small amounts including mouth rinse
During endurance exercise including “stop and start”
sports (1-2.5 hrs)
30-60 g/hr
During ultra-endurance exercise (2.5-3 hrs)
Up to 90 g/hr using multiple transportable carbohydrates
(glucose: fructose mix)
Speedy refuelling when there is <8 hrs recovery
between two fuel demanding sessions
1-1.2 g/kg body weight every hr for first 4 hrs then resume
daily fuel needs
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FA CT S H E ET
CONTINUED
Where does sugar fit in the diet?
Carbohydrates can be broadly categorised into sugars, starches and dietary fibre, all of which
are dealt with quite differently by the body.4
An athlete with inadequate carbohydrate intake or stores may suffer from fatigue, reduced
ability to train hard, impaired cognitive performance, and a reduction in immune system
function. Hence, athletes who train for longer than 45 minutes may require higher
carbohydrate intakes than the general population.2
An athlete’s individual carbohydrate requirements are dependent on the fuel needs of their
training and competition programme, but Table 1, provides general targets from the
Australian Institute of Sport.2
Before exercise:
Building energy stores for the event
Excess glucose is stored in the muscles as
glycogen. The amount of glycogen in the
muscles at the start of exercise is seen to be
proportional to the amount of time an
athlete can perform before exhaustion or
fatigue sets in.
Carbohydrate loading for endurance
athletes is a strategy used to increase
muscle glycogen stores. It involves changes
to training and nutrition patterns one to four
days before an endurance event. The
Australian Institute of Sport suggests that
carbohydrate loading is appropriate for
anyone exercising for 90 minutes or longer,
for example marathon runners or
triathletes.5
Carbohydrate loading enables the muscle
glycogen levels to be increased from the
normal range of 100-120mmol/kg ww (wet
weight) to around 150-200mmol/kg ww. In
the past carbohydrate loading was
preceded by a period of carbohydrate
depletion. However, now the experts
recommend exercise taper combined with a
high carbohydrate diet (7-12 g/kg body
weight) one to four days prior to the event to
elevate muscle glycogen levels.5 The extra
supply of carbohydrate can help improve
performance over a set distance by 2-3%
allowing the athlete to exercise for a longer
period of time.5
When carbohydrate loading it is suggested
to stick to high-carbohydrate, low-fat foods
as it can help athletes meet the higher
carbohydrate requirements during this time.
It is also helpful to cut back on fibre and
make use of compact, readily digestible
sources of carbohydrate such as sugar,
cordial, soft drink, sports drink, jam, honey,
jelly and tinned fruit. Athletes who include
too many high fibre foods in their
carbohydrate loading menu may suffer
gastro-intestinal discomfort or find the food
too bulky to consume. Consuming too
many high fat foods will also make it difficult
to consume sufficient carbohydrate.5
A general guide is to have a meal about 3-4
hours before exercise or a lighter snack 1-2
hours before exercise. It has been
suggested that low GI foods could be useful
in the pre-event meal as they would result in
a slower and more sustained release of
glucose during exercise, maintaining blood
glucose levels for a longer period. However,
consuming low GI foods prior to exercise
has not been associated with universal
benefits
on
exercise
performance.
Consuming carbohydrate (e.g. sports drink)
during exercise can provide an alternative
way to maintain fuel levels throughout the
activity and this practice may override the
effects of different types of carbohydrate in
the pre-event meal.
Athletes wishing to achieve optimum results
should also consider working with a sports
dietitian who can prepare a carb-loading
plan to individual needs.
During exercise:
Getting the most
from the event
Performance and enjoyment of an event will
be enhanced if the athlete has the right fuel
on board. The appropriate carbohydrate
food or drink to consume generally depends
on the athlete’s previous experience, the type
of event, gastrointestinal comfort and the
need for fluid replacement.
If the event duration is greater than 45
minutes then carbohydrate intake during the
event may be beneficial (Table 1 provides
some general targets).
While the GI of foods consumed during
exercise has not been thoroughly studied,
athletes typically choose moderate to high GI
carbohydrate sources, such as specifically
developed sports drinks or sports gels.
The optimum source and concentration of
carbohydrate will depend on individual
circumstances, so trialing different types of
sports drinks and foods prior to competing is
suggested as this can help determine which
products work for you.
The ingestion of glucose during prolonged
intense
exercise
can
prevent
the
development of hypoglycaemia (low blood
glucose) by maintaining or raising the
circulating glucose concentration.6 As a
result, an improvement in performance is
consistently observed with the provision of
additional fuel during prolonged moderate
intensity or intermittent high-intensity
exercise.7
Adequate hydration is also very important.
When exercising or participating in an event
for longer than 30 minutes, fluid top ups are
needed. Water is sufficient for many athletes
but if the duration of the event or training is
longer than an hour then individuals may
benefit from consuming sports drinks.7
Sports drinks can be an efficient option
during an event as they provide carbohydrate
and fluid. Sports drinks use glucose, glucose
polymers, sucrose and fructose as a
carbohydrate
source,
with
a
total
carbohydrate concentration of 4-8% (4-8
g/100mL). Most sports drinks also contain
sodium (typically 10-30mmol/L), which is an
electrolyte replacement and also aids in the
absorption of sugar.7 A specially formulated
sports drink is likely to be more effective than
a standard juice or soft drink.7
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FACT SH E ET
After exercise:
Rebuilding energy stores after the event
Refueling after exercise or an event is as important as before and during activity. Recovery from exercise is not a passive process. Tissues
undergo repair and reproduction, fluid balance is restored and glycogen stores are replaced. Carbohydrate replacement is one of the most
important strategies as the muscle enzymes are receptive to glucose. There is a direct and positive relationship between the quantity of
carbohydrate consumed and post-exercise glycogen storage.8 It appears that high GI foods achieve better post-exercise glycogen storage.9
Examples of high GI foods that could be eaten after an event include; sports drinks, some breakfast cereals, jam sandwiches and jellybeans.
Not replenishing energy stores may result in low muscle stores, which could lead to early fatigue and poor sports ongoing performance. Injuries
and the onset of illness can affect athletes who have low glycogen levels and can occur from 3-72 hours after prolonged exercise (greater than
90 minutes) when immune function may be reduced. To protect against this, having carbohydrate drinks (60g carbohydrate per hour) before,
during and after exercise have been shown to raise plasma glucose levels.10
For athletes who have several competitions in a row, it is suggested that carbohydrate replacement should be a priority. The source and
spacing of carbohydrates is important to reduce the likelihood of gastrointestinal upsets when competing. Between competitions athletes may
find avoiding high fibre and high fat foods helpful, instead opting for white breads, rice, low fibre cereals or a liquid meal.
Types of carbohydrates
The digestion of carbohydrates is useful for athletes to understand. The digestion process breaks down carbohydrates into glucose, which
provides energy to our body, commonly called blood glucose. Excess glucose is stored in the muscles as glycogen, which is used by
exercising muscles.
The speed of the breakdown of carbohydrate foods into glucose and its subsequent effect on raising blood glucose varies greatly between
individuals and is mainly dependent on the overall composition of the food. For example a slice of bread may contain dietary fibre, wheat starch
and a small amount of sugar. The breakdown of all these carbohydrate components is interlinked.
Sugars and
starches
Total sugars include monosaccharides,
disaccharides, polysaccharides (starches)
and polyols.4
All go through a complicated digestion
process to ultimately produce glucose.
Sugars include glucose, fructose, lactose,
maltose and sucrose (table sugar). Sugars
are the least complicated of carbohydrates,
meaning they are easily digested and
absorbed. Hence, an athlete who wants a
quick burst of energy during an event might
consume a sugary food such as lollies. But if
an athlete needs energy over a more
extended time period consuming sugar as
part of a mixed meal may slow the digestion
of the carbohydrate to give a more steady
flow of energy.
Carbohydrate quality
Many foods and drinks contain carbohydrates. When it comes to choosing what sources of
carbohydrate an athlete should use it is not as simple as just looking at the total carbohydrate
content, or even considering carbohydrate type. High quality carbohydrate foods are
generally nutrient-dense, meaning that there are other beneficial nutrients in addition to
carbohydrate, and these should be the primary source of carbohydrate in all athletes’ diets.2
Nutrient-poor carbohydrate foods may be beneficial occasionally by providing a compact and
readily digestible carbohydrate source around training. From a sports nutrition point of view,
the Australian Institute of Sport categorizes carbohydrates as nutrient-dense, nutrient-poor or
high-fat, and provides recommendations for how these separate groups should fit into an
athlete’s diet (Table 2).2
Dietary fibre
Dietary fibre is described as being resistant to digestion and absorption in the small intestine.4
However; this can be misleading as some dietary fibre is digested. This takes place in the
large intestine rather than in the stomach by normal digestive processes.
These carbohydrates move through the body’s system relatively unchanged. Dietary fibre
confers many benefits including slowing the release of energy from foods, stabilising blood
glucose levels, as well as keeping our digestive tract healthy.
Sugars and starches are found in
carbohydrate-rich foods such as breads,
cereals, pastas, fruits and vegetables as well
as many pre-prepared and ready to eat
meals and beverages.
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FA CT S H E ET
TABLE 2: CARBOHYDRATE CATEGORIES FROM A SPORTS NUTRITION PERSPECTIVE2
CATEGORY
DESCRIPTION
EXAMPLES
USE FOR ATHLETES
Nutrient-dense
carbohydrate
Foods and drinks that are rich
sources of other nutrients including
protein vitamins, minerals, fibre and
antioxidants in addition to
carbohydrate
Breads and cereals grains (e.g.
pasta, rice), fruit starchy vegetables
(e.g. potato, corn) legumes and
low-fat dairy products
Everyday food that should form the
base of an athlete’s diet. Helps to
meet other nutrient targets
Nutrient-poor
carbohydrate
Foods and drinks that contain
carbohydrate but minimal or no
other nutrients
Soft drinks, energy drinks lollies,
carbohydrate gels sports drink and
cordial
Shouldn’t be a major part of the
everyday diet but may provide a
compact carbohydrate source
around training
High-fat carbohydrate
Foods that contain carbohydrate
but are high in fat
Pastries, cakes, chips (hot and
crisps) and chocolate
‘Sometimes’ foods best not
consumed around training
sessions
The Glycaemic Index (GI) is another tool for athletes to work out what food suits them best for their sport and personal choice. Glycaemic Index
is a ranking of how quickly carbohydrate foods raise blood glucose levels in the body following ingestion. Athletes who need a quick release
of energy from their food could benefit from consuming high GI foods, while those who need a sustained release of food energy, such as
endurance athletes, may benefit from consuming low GI foods.2 Refer to the Glycaemic Index website for more information
(www.glycemicindex.com).
Conclusion
A balanced diet made up of a variety of foods can make a real difference to a sports person’s performance and exercise enjoyment.
An integral and valuable part of such a diet is carbohydrate, which can include sugars.
Last updated August 2014
REFERENCES
1. Burke, L M. Dietary carbohydrates. In: The Encyclopaedia of Sports Medicine. Vol VII Nutrition in
Sport, edited by R.J. Maughan. Oxford: Blackwell Science, 2000, p.73-84. Sourced from
http://www.ausport.gov.au/ais/nutrition/research/overview)
2. Australian Institute of Sport. Sports Nutrition 2014 Fact Sheet: Carbohydrate- the facts. Available
at: http://www.ausport.gov.au/ais/nutrition/factsheets/basics/carbohydrate__how_much
3. Millennium Institute of Sport & Health & Nestle New Zealand, 2009. Carbohydrate and sports
performance. Available at: http://www.autmillennium.org.nz/wpcontent/uploads/2013/01/CARBOHYDRATE.pdf
4. Cummings JH and Stephen AM. Carbohydrates terminology and classification. FAO/WHO
scientific update on carbohydrates in human nutrition. Eur J Clin Nutr. Dec 2007;61 Suppl
1:S5-18
5. Australian Institute of Sport. Sports Nutrition 2009 Fact Sheet: Carbohydrate loading. Available
at: http://www.ausport.gov.au/ais/nutrition/factsheets/competition_and_training/carbohydrate_loading
6. Wilmore, J.H. & Costill, DL. (1994) Physiology of Sport end Exercise, Human Kinetics, USA
7. Australian Institute of Sport. Sports Nutrition 2009 Fact sheet: Fluid- who needs it? Available at:
http://www.ausport.gov.au/ais/nutrition/factsheets/hydration/fluid_-_who_needs_it
8. Burke LM, Kiens B, Ivy JL. Carbohydrates and fat for training and recovery. J Sports Sci.
2004;22(1):15-30.
9. Burke & Deakin (2007). Clinical Sports Nutrition. 3rd edition. McGraw-Hill, Sydney
The Sugar Research
Advisory Service (SRAS)
is a scientific information
service, advised by a
panel of independent
health and nutrition
experts. To contact SRAS
and for further
information please go to
www.SRASANZ.org
Contact details are:
The Secretariat
SRAS
PO Box 5224
Wellesley Street
Auckland
Fax 09 308 9456
Email [email protected]
10. Exercise Immunology review 4: 64-76, 1998
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