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chapter
Nutritional
10
Factors in Health and
Performance
Nutritional Factors
in Health and
Performance
Kristin Reimers, PhD, RD
Chapter Objectives
• Identify the protein, carbohydrate, and fat recommendations for athletes.
• Discern between dietary recommendations for
disease prevention and recommendations for
performance.
• Identify and apply appropriate hydration practices
for athletes.
• Apply precompetition and posttraining eating
strategies and advise athletes on guidelines for
weight gain and weight loss.
(continued)
Chapter Objectives (continued)
• Recognize signs and symptoms of eating disorders.
• Understand the importance of having an intervention and referral system in place for athletes
suspected of having an eating disorder.
• Recognize the prevalence and etiologies of obesity.
• Assist in the assessment process for obese
individuals.
Section Outline
• Role of the Nutritionist
Role of the Nutritionist
• Responsibilities of the nutritionist include
the following:
– Personalized nutritional counseling: weight loss and
weight gain, strategies to improve performance,
menu planning, dietary supplements
– Dietary analysis of food records
– Nutritional education: presentations and handouts
– Referral and treatment of eating disorders
Section Outline
• How to Evaluate the Adequacy of the Diet
– Standard Nutrition Guidelines
– Dietary Reference Intakes
How to Evaluate
the Adequacy of the Diet
• Standard Nutrition Guidelines
– Most athletes have two basic dietary goals:
• Eating to maximize performance
• Eating for optimal body composition
How to Evaluate
the Adequacy of the Diet
• Standard Nutrition Guidelines
– Food Guide Pyramid
• Used to evaluate appropriate calorie level
• Used to evaluate appropriate nutrient levels to prevent
nutrient deficiency or toxicity
• Developed by the U.S. Department of Agriculture in 1992
• Updated to MyPyramid in 2005
MyPyramid
• Figure 10.1 (next slide)
– Displays recommended types and amounts of food
to eat daily
– For more information and resources, go to
www.mypyramid.gov
Figure 10.1
How to Evaluate
the Adequacy of the Diet
• Standard Nutrition Guidelines
– The color bands of MyPyramid represent five food
groups that are needed each day for health:
•
•
•
•
•
Grains
Vegetables
Fruits
Milk
Meat and beans
Key Point
• MyPyramid is an excellent starting point
from which to evaluate the adequacy of an
athlete’s diet. If a diet provides a variety of
foods from each group, it is likely adequate
for vitamins and minerals. However, if the
diet excludes an entire food group, specific
nutrients may be lacking.
Table 10.1
How to Evaluate
the Adequacy of the Diet
• Dietary Reference Intakes
– In 2005, the DRIs replaced the “Recommended
Dietary Allowances.”
– The DRI for each nutrient includes the following:
• Estimated average requirement and its standard deviation
by age and gender
• Recommended dietary consumption based on the
estimated average requirement
• An adequate intake level when a recommended intake
cannot be based on an estimated average requirement
• Tolerable upper intake levels above which risk of toxicity
increases
Section Outline
• Macronutrients
– Protein
• Structure and Function of Proteins
• Dietary Protein
• Protein Requirements
– General Requirements
– Increased Requirements for Athletes
(continued)
Section Outline (continued)
• Macronutrients
– Carbohydrates
•
•
•
•
•
Structure and Sources of Carbohydrates
Dietary Carbohydrate
Glycemic Index
Fiber
Carbohydrate Requirements
– Lipids
•
•
•
•
Structure and Function of Lipids
Fat and Disease
Fat Requirements and Recommendations
Fat and Performance
Macronutrients
• A macronutrient is a nutrient that is
required in significant amounts in the diet.
• Three important classes of macronutrients
are protein, carbohydrates, and lipids.
Macronutrients
• Protein
– Structure and Function of Proteins
• More than half of the amino acids can be synthesized by
the human body and are commonly called “nonessential”
amino acids because they do not need to be consumed in
the diet.
• Nine of the amino acids are “essential” because the body
cannot manufacture them and therefore they must be
obtained through the diet.
• Proteins provide 4 kcal/g.
Table 10.2
Macronutrients
• Protein
– Dietary Protein
• high-quality (complete) protein: A protein with an amino
acid pattern similar to that needed by the body. Usually of
animal origin.
• low-quality (incomplete) protein: A protein that is deficient in
one or more of the essential amino acids. Usually of plant
origin.
Macronutrients
• Protein
– Protein Requirements
• General Requirements
– Assuming that caloric intake is adequate and that two-thirds
or more of the protein is from animal sources, the recommended intake for protein for adults is 0.8 g/kg (0.36 g/pound)
of body weight for both men and women.
– Expressed as a percent of daily caloric intake, a common
protein intake recommendation is 10% to 15%.
Key Point
• Recommendations to increase or decrease
protein intake should be made on an individual basis after the normal diet has been
analyzed and caloric intake considered. A
mixed diet is the best source of high-quality
protein. Strict vegetarians must plan their
diet carefully to ensure an adequate intake
of all essential amino acids.
Macronutrients
• Protein
– Protein Requirements
• Increased Requirements for Athletes
– Based on current research, it appears that the protein
requirements for athletes are between 1.5 and 2.0 g/kg
of body weight, assuming that caloric intake and protein
quality are adequate.
Macronutrients
• Carbohydrates
– The primary role of carbohydrate in human
physiology is to serve as an energy source.
– Carbohydrates provide 4 kcal/g.
Macronutrients
• Carbohydrates
– Structure and Sources of Carbohydrates
• Monosaccharides (glucose, fructose, and galactose) are
single-sugar molecules.
• Disaccharides (sucrose, lactose, and maltose) are
composed of two simple sugar units joined together.
• Polysaccharides, also known as complex carbohydrates,
contain up to thousands of glucose units.
Macronutrients
• Carbohydrates
– Dietary Carbohydrate
• All types of dietary carbohydrate—sugars as well as
starches—are effective in supplying the athlete with
glucose and glycogen.
• Consumption of a mix of sugars and starches is desirable.
Macronutrients
• Carbohydrates
– Glycemic Index
• The GI classifies a food by how high and for how long it
raises blood glucose.
• The reference food is glucose or white bread (GI = 100).
• Foods that are digested quickly and raise blood glucose
(and insulin) rapidly have a high GI.
• Foods that take longer to digest and thus slowly increase
blood glucose (and therefore stimulate less insulin) have a
low GI.
Glycemic Index (GI) of Various Foods
• Table 10.3 (next slide)
– The table uses white bread (GI = 100) as a
standard.
– When variations exist in a food item, the mean is
reported.
Table 10.3
Adapted, by permission, from Foster-Powell, Holt, and Brand-Miller, 2002.
Macronutrients
• Carbohydrates
– Fiber
• The DRI for fiber is 38 and 25 g/day for young men and
women, respectively.
• This level of fiber may be excessive for some aerobic
endurance athletes.
– Carbohydrate Requirements
• The general recommendation is to consume 50% to 55%
of total daily calories as carbohydrate.
• Aerobic endurance athletes who train for long durations
(90 minutes or more daily) should replenish glycogen levels
by consuming maximal levels of carbohydrate, approximately 8 to 10 g/kg of body weight.
Key Point
• Some aerobic endurance athletes have
maximal carbohydrate requirements, up to
10 g/kg per day. Most athletes do not
deplete muscle glycogen on a daily basis,
however, and therefore have lower carbohydrate requirements.
Macronutrients
• Lipids
– Structure and Function of Lipids
• Fatty acids containing no double bonds are saturated.
• Fatty acids containing one double bond are monounsaturated.
• Fatty acids containing two or more double bonds are
polyunsaturated.
• Fats provide approximately 9 kcal/g.
Macronutrients
• Lipids
– Fat and Disease
• High levels of cholesterol or unfavorable ratios of
lipoproteins are associated with increased risk of heart
disease.
• High levels of HDLs protect against heart disease.
• HDLs can be increased by exercise and weight loss.
Table 10.4
Macronutrients
• Lipids
– Fat Requirements and Recommendations
• The recommendation for the general public from health
organizations such as the American Heart Association is
that fat should constitute 30% or less of the total calories
consumed.
• It is recommended that 20% of the total calories (or twothirds of the total fat intake) come from monounsaturated or
polyunsaturated sources and 10% from saturated fats (onethird of total fat intake).
(continued)
Macronutrients
• Lipids
– Fat Requirements and Recommendations
(continued)
• The Sub-Committee on Nutrition of the United Nations
recommends an upper limit for fat intake of 35% of total
calories for active people.
• The American Heart Association and the Sub-Committee
on Nutrition of the United Nations recommend that fat
provide at least 15% of the total calories in the diets of
adults and at least 20% of total calories in the diets of
women of reproductive age.
Key Point
• Fat phobia, or fear of eating fat, can lead
to nutrient deficiencies, which harm
performance. Athletes who eat very little
or no fat should receive nutritional counseling and information.
Macronutrients
• When Should Athletes Decrease Dietary
Fat?
– Need to increase carbohydrate intake to support
training type
• In this case, to ensure adequate protein provision, fat is the
nutrient of choice to decrease so that that caloric intake can
remain similar while carbohydrate is increased.
Macronutrients
• When Should Athletes Decrease Dietary
Fat?
– Need to reduce total caloric intake to achieve weight
loss
• Because fat is dense in calories and is highly palatable,
decreasing dietary fat, if the diet has excess fat, can help
reduce caloric intake.
– Need to decrease elevated blood cholesterol
• Some young athletes are strongly predisposed to heart
disease, although this is uncommon.
Macronutrients
• Lipids
– Fat and Performance
• Intramuscular fatty acids are more important during activity.
• Circulating fatty acids (from adipose tissue or diet) are more
important during recovery.
• Consumption of high-fat diets may enhance performance
and result in longer distance to exhaustion.
• The effects of high-fat diets vary, depending on the
individual.
Section Outline
• Micronutrients
– Vitamins
– Minerals
• Iron
• Calcium
Micronutrients
• A micronutrient is a nutrient that is required
in small amounts (typically measured in
milligram—or even smaller—quantities) in
the diet.
• Two primary types of micronutrients are
vitamins and minerals.
Micronutrients
• Vitamins
– Vitamins are organic substances (i.e., containing
carbon atoms) that cannot be synthesized by the
body.
– They are needed in very small amounts and perform
specific metabolic functions.
Table 10.5
(continued)
(continued)
Table 10.5 (continued)
Micronutrients
• Minerals
– Minerals are required for a wide variety of metabolic
functions.
– For athletes, minerals are important for bone health,
oxygen-carrying capacity, and fluid and electrolyte
balance.
Table 10.6
(continued)
Table 10.6 (continued)
(continued)
Micronutrients
• Minerals
– Iron
• Iron is a constituent of hemoglobin and myoglobin and,
as such, plays a role in oxygen transport and utilization
of energy.
Micronutrients
• Minerals
– Calcium
• Athletes who consume low-calcium diets may be at risk for
osteopenia and osteoporosis (deterioration of bone tissue
leading to increased bone fragility and risk of fracture).
Section Outline
• Fluid and Electrolytes
– Water
• Fluid Balance
• Risks of Dehydration
• Monitoring Hydration Status
– Electrolytes
– Fluid Replacement
• Before Activity
• During Activity
• After Activity
Fluid and Electrolytes
• Water
– Water is the largest component of the body,
representing from 45% to 70% of a person’s body
weight.
– Total body water is determined largely by body
composition; muscle tissue is approximately 75%
water, whereas fat tissue is about 20% water.
Fluid and Electrolytes
• Water
– Fluid Balance
• The average fluid requirement for adults is estimated to be
2 to 2.7 quarts (1.9-2.6 L) per day.
• Athletes sweating profusely for several hours per day may
need to consume an extra 3 to 4 gallons (11-15 L) of fluid
to replace losses.
Fluid and Electrolytes
• Water
– Risks of Dehydration
• Fluid loss equal to as little as 1% of total body weight can
be associated with an elevation in core temperature during
exercise.
• Fluid loss of 3% to 5% of body weight results in cardiovascular strain and impaired ability to dissipate heat.
• At 7% loss, collapse is likely.
Key Point
• Consuming adequate fluids before, during,
and after training and competition is
essential to optimal resistance training
and aerobic endurance exercise.
Fluid and Electrolytes
• Water
– Monitoring Hydration Status
• Each pound (0.45 kg) lost during practice represents
1 pint (0.5 L) of fluid loss.
• Signs of dehydration include the following:
–
–
–
–
Dark yellow, strong-smelling urine
Decreased frequency of urination
Rapid resting heart rate
Prolonged muscle soreness
Fluid and Electrolytes
• Electrolytes
– The major electrolytes lost in sweat are sodium
chloride, and, to a lesser extent, potassium.
• Fluid Replacement
– The ultimate goal is to start exercise in a hydrated
state, avoid dehydration during exercise, and
rehydrate before the next training session.
Fluid and Electrolytes
• Fluid Replacement Guidelines
– Before a Training Session
• Encourage athletes to hydrate properly before prolonged
exercise in a hot environment.
• Intake should be approximately 16 fluid ounces (0.5 L) of a
cool beverage 2 hours before a workout.
Fluid and Electrolytes
• Fluid Replacement Guidelines
– During a Training Session
• Provide cool beverages (about 50-70 °F [10-21 °C]).
• Have fluids readily available, since the thirst mechanism
does not function adequately when large volumes of water
are lost.
• Athletes need to be reminded to drink.
• Athletes should drink fluid frequently—for example,
6 to 8 fluid ounces (177-237 ml) every 15 minutes.
Fluid and Electrolytes
• Fluid Replacement Guidelines
– After a Training Session
• Athletes should replenish fluids with at least 1 pint (0.5 L)
of fluid for every pound (0.45 kg) of body weight lost.
• Weight should be regained before the next workout.
• Water is an ideal fluid replacement, although flavored
beverages may be more effective at promoting drinking.
• The ideal fluid replacement beverage depends on the
duration and intensity of exercise, environmental
temperature, and the athlete.
Section Outline
• Precompetition and Postexercise Nutrition
– Precompetition Food Consumption
•
•
•
•
Purpose
Timing
Practical Considerations
Carbohydrate Loading
– Postexercise Food Consumption
Precompetition and
Postexercise Nutrition
• Precompetition Food Consumption
– Purpose
• The primary purpose is to provide fluid and energy for the
athlete during the performance.
– Timing
• The most common recommendation is to eat 3 to 4 hours
prior to the event to avoid becoming nauseated or uncomfortable during competition.
Precompetition and
Postexercise Nutrition
• Precompetition Food Consumption
– Practical Considerations
• It is important for athletes to consume food and beverages
that they like, that they tolerate well, that they are used to
consuming, and that they believe result in a winning
performance.
Key Point
• The primary goal of the precompetition meal
is to provide fluid and energy for the athlete
during performance.
Precompetition and
Postexercise Nutrition
• Precompetition Food Consumption
– Carbohydrate Loading
• Carbohydrate loading is a technique used to enhance
muscle glycogen prior to long-term aerobic endurance
exercise.
Precompetition and
Postexercise Nutrition
• Postexercise Food Consumption
– Data suggest that high-GI foods consumed after
exercise replenish glycogen faster than low-GI
foods.
– Although emphasis is usually placed on carbohydrate, in practical terms, consuming a balanced
meal ensures the availability of all substrates for
adequate recovery, including amino acids.
Section Outline
• Weight and Body Composition
– Energy Requirements
• Factors Influencing Energy Requirements
• Estimating Energy Requirements
– Weight Gain
– Weight Loss
– Rapid Weight Loss
Weight and Body Composition
• Energy Requirements
– Energy is commonly measured in kilocalories (kcal
or calories).
– A kilocalorie is the work or energy required to raise
the temperature of 1 kg of water 1 °C (or 2.2
pounds of water 1.8 °F).
– Energy (caloric) requirement is defined as energy
intake equal to expenditure, resulting in constant
body weight.
Weight and Body Composition
• Energy Requirements
– Factors Influencing Energy Requirements
• Resting metabolic rate
• Thermic effect of food
• Physical activity
Key Point
• There is a wide range of energy expenditures and energy intakes among sports due
to differences in body mass, intensity of
training, work efficiency, and the size of the
involved muscle mass.
Weight and Body Composition
• Energy Requirements
– Estimating Energy Requirements
• Energy needs can be loosely estimated using the
guidelines found in table 10.7.
• Athletes can also use food diaries during periods of stable
body weight to estimate requirements.
Table 10.7
Weight and Body Composition
• Weight Gain
– If all the extra calories consumed are used for
muscle growth during resistance training, then
about 2,500 extra kilocalories are required for
each 1-pound (0.45 kg) increase in lean tissue.
Key Point
• Gains in body mass and strength occur
when the athlete consumes adequate
calories and dietary protein and engages in
a progressive resistance training program.
Weight and Body Composition
• Weight Loss
– If all the expended or dietary-restricted kilocalories
apply to body fat loss, then a deficit of 3,500 kcal will
result in a 1-pound (0.45 kg) fat loss.
– The maximal rate of fat loss appears to be approximately 1% of body mass per week.
– This is an average of 1.1 to 2.2 pounds (0.5-1.0 kg)
per week and represents a daily caloric deficit of
approximately 500 to 1,000 kcal.
Key Point
• The most important goal for weight loss is
to achieve a negative calorie balance.
Therefore, the types of foods the individual
consumes are less important than the
portions of those foods. The focus is on
calories.
Weight and Body Composition
• Rapid Weight Loss
– For athletes who desire to minimize lean tissue loss,
small decreases in caloric intake to achieve gradual
weight loss are indicated.
Section Outline
• Eating Disorders: Anorexia Nervosa
and Bulimia Nervosa
– Definitions and Criteria
– Management and Care
• Steps in the Management of Eating Disorders
• What Not to Do
Eating Disorders: Anorexia Nervosa
and Bulimia Nervosa
• Definitions and Criteria
– Anorexia nervosa is self-imposed starvation in an
effort to lose weight and achieve thinness.
– Bulimia nervosa is characterized by recurrent
consumption of food in amounts significantly greater
than would customarily be consumed at one sitting.
Figure 10.2
Reprinted, by permission, from American Psychiatric Association, 1994.
Figure 10.3
Reprinted, by permission, from American Psychiatric Association, 1994.
Eating Disorders: Anorexia Nervosa
and Bulimia Nervosa
• Definitions and Criteria
– Warning Signs for Anorexia Nervosa
• Commenting repeatedly about being or feeling fat
• Asking questions such as “Do you think I’m fat?” when
weight is below average
• Dramatic weight loss for no medical reason
• Reaching a weight that is below the ideal competitive
weight
• Continuing to lose weight even during the off-season
• Preoccupation with food, calories, and weight
Eating Disorders: Anorexia Nervosa
and Bulimia Nervosa
• Definitions and Criteria
– Warning Signs for Bulimia
• Eating secretively
• Disappearing repeatedly immediately after eating
• Appearing nervous if something prevents the person from
being alone after eating
• Losing or gaining extreme amounts of weight
• Smell or remnants of vomit in the rest room or elsewhere
• Disappearance of large amounts of food
Eating Disorders: Anorexia Nervosa
and Bulimia Nervosa
• Definitions and Criteria
– Warning Signs for Both Disorders
•
•
•
•
•
•
•
•
Complaining frequently of constipation or stomachaches
Mood swings
Social withdrawal
Relentless, excessive exercise
Excessive concern about weight
Strict dieting followed by binges
Increasing criticism of one’s body
Strong denial that a problem exists even when there is
hard evidence
Eating Disorders: Anorexia Nervosa
and Bulimia Nervosa
• Management and Care
– Steps in the Management of Eating Disorders
•
•
•
•
Fact finding
Confronting
Referring
Following up
Eating Disorders: Anorexia Nervosa
and Bulimia Nervosa
• Management and Care
– What Not to Do
• The strength and conditioning professional’s job is not to
treat an eating disorder; it is to be aware of warning signs
and to refer when a problem is suspected.
Section Outline
• Obesity
Table 10.8
Key Point
• Obesity is not the same condition in each
individual. Thorough assessment helps
determine which treatment is appropriate
and, more important, whether the individual
is ready for treatment.