Chapter 10
Lecture Slides
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Weight Control
• Weight control for health
– Mental health
• Body image
• Fattism
– Physical health
• Obesity
• Anorexia
• Weight control for
performance
– Weight-control sports
• Running
– Muscle-mass sports
• American football
Body Weight and Body Image
• Dissatisfied with current body weight
– 40% of American men
– 55% of American women
– Many high school and elementary school students
• Desire to change current body weight
– 85% of first-year male and female college
students
• Females: Leanness
• Males: Muscularity
Obesity
• World Health Organization
– 1 billion people overweight
– 300 million are obese
Obesity
• United States
– Rate of obesity increasing over
past 30 years
– 2 out of 3 adults are
overweight or obese
– Extreme obesity increasing at
alarming rates
• 1 in 200 in 1986
• 1 in 50 today
– Overweight and obesity
increasing rapidly in children
• About 25% will be overweight or
obese by 2015
Body Weight and Composition
What is the ideal body weight?
• Ideal for what?
– Health
– Appearance
– Sport performance
• Concept of Healthy Body Weight
– The Body Mass Index (BMI)
• Also known as Quetelet’s Index
Body Mass Index
• A height to weight ratio
– Body weight in KG ÷ (Height in meters)²
– Body weight in lbs x 705 ÷ (Height in inches)²
• Normal BMI = 18.5 – 25.0
What are the values and limitations of the BMI?
• Value
– A screening device for both underweight and
obesity, both of which may be related to health
problems
– May be a useful guide to body weight for the
average individual
• Limitations
– Does not evaluate body composition
• Some classified as overweight may have low body fat
• Some classified as normal weight may have excess fat
What is the composition of the body?
• The human body is composed of earth’s elements
– Carbon, hydrogen, oxygen, nitrogen
– Calcium, phosphorus, iron, magnesium, and others
• Elements in combination
–
–
–
–
–
Carbohydrate
Fat
Protein
Water
Minerals
Body composition components
• Four major body components and their densities
– Density = mass ÷ volume [g/ml or g/cc)
•
•
•
•
Body water (Density = 1.0)
Total body fat (Density = 0.9)
Fat free mass (Density = 1.1)
Bone mineral (Density = 1.3 – 1.4)
• Determination of body composition is usually done
by calculating total body density
Body composition
• Total body fat
– Essential fat
• Males (3%)
• Females (12-15%)
– Storage fat
• Subcutaneous fat
– Cellulite
• Visceral fat
Body composition
• Fat-free mass
– Protein and water
– Lean body mass
• Includes essential fat
Body composition
• Bone mineral
– 50% water
– 50% protein and
minerals
– Total bone weight,
including protein and
water, may constitute
12-15% of body weight
Body water
• Body water compartments
– Intracellular
– Intercellular
– Extracellular
• Normal water levels
– 60% of body weight in average-weight male
– 50% of body weight in average-weight female
• Fat-free mass and body fat
– Muscle is about 70% water
– Fat is about 10% water
What techniques are available to measure body
composition and how accurate are they?
• Direct analysis of body fat
– Chemical extraction
• Indirect analysis of body fat
– All techniques currently used with living humans are
indirect
– All techniques are subject to measurement error
– Two-component models have highest error
– Three- and four-component models help reduce error
Body composition
• Measurement error
– Standard error of measurement
(SEM)
– May vary with body fat
measurement techniques
• Normal curve
– 70% of population within ± 1
SEM
– 95% of population within ± 2
SEM
• Assume skinfold technique
predicts 17% body fat and
SEM is 3%
– 70% chance body fat is between
14-20%
Underwater weighing
• Hydrodensitometry
• Based on Archimedes’
principle
– Buoyancy of water
displacement
• Previously was the gold
standard
• SEM is about 2.0 - 2.5%
Air Displacement Plethysmography (APD)
• Based on air
displacement
• Advantages over
underwater weighing
• Reliable method in
testing same subject
over time
Skinfolds technique
• Measure of
subcutaneous fat
– Skinfold calipers
– Ultrasound
• SEM about 3-4%
• Use population-specific
formulae
• Good practical method
• Used by NCAA for
wrestlers
Dual Energy X-ray Absorptiometry
(DXA;DEXA)
• Computerized X-ray
• Concurrent measures
– Bone mineral
– Body mat
– Fat-free mass
• Some contend it is the
criterion method
• Others
– Computed tomography
– Magnetic resonance
imaging
Body composition
• Other methods
– Bioelectrical impedance analysis
– Infrared interactance
– Anthropometry
• Regional fat distribution
• Waist circumference
– Multicomponent models
• Use combination of methods
• Some consider it the new gold standard
What problems may be associated with rigid
adherence to body fat percentages in sport?
• The SEM for the measurement technique may be
high
• Example of potential problem
–
–
–
–
Skinfold technique predicts body fat as 8% in young athlete
Coach wants athlete to reduce to 5%
If SEM is 3%, the athlete may already be at 5%
Losing excess weight in such an athlete may come at the
expense of losing muscle tissue
How much should I weigh or how much
body fat should I have?
• A complex question
• Physical appearance
– Individual’s perception
– May lead to health problems
• Sport performance
– May be benefits of weight
loss or weight gain
• Health
– Some guidelines for health
improvement
Body mass index
• Screening for health
BMI
Health Risks
< 18.5
May signal malnutrition or serious disease
18.5-24.9
Healthy weight range that carries little health
risk
25-25.9
Overweight; at increased risk for health
problems, especially if you have one or two
weight-related medical conditions
Above 30
Obesity, more than 20 percent over healthy
body weight; poses high risk to your health
• Some classify a BMI of 35 or 40 as morbid obesity
Body fat percentage
• Recommendations for health /performance vary
Waist circumference
• Measure of regional fat distribution
Regulation of Body Weight and
Composition
How does the human body normally
control its own weight?
• Male college student
• Consume about 1
million Calories a year
– 2,700 Calories daily
• Not gain one pound
• Set-point theory
– Energy intake balanced
with energy expenditure
– Role of the
hypothalamus
The set-point theory of weight control
Comparable to the set-point for temperature control.
Instead of a set point for body temperature, there is a
set point for body weight
The set-point theory:
Energy intake
• Appestat
– Hunger center
– Satiety center
• Afferent stimuli
– Senses
– Stomach fullness
– Blood nutrient levels
• Glucostat; lipostat; aminostat
– Body temperature
– Hormones and neuropeptides (neurotransmitters)
The set-point theory:
Energy expenditure
• Basal energy expenditure (BEE)
– Brown fat
• Uncoupling proteins (UCP)
• Uncouple oxidation from ATP formation
– White fat tissue and muscle tissue
• UCPs
– Hormones
• Thyroid hormones; epinephrine
The set-point theory:
Energy expenditure
• Nonexercise activity
thermogenesis (NEAT)
– All activity except
sleeping, eating, and
sports-like exercise
The set-point theory:
Feedback control of energy intake & expenditure
• Short-term mechanisms
– May ↑ or ↓ food intake
– Expansion or contraction of
stomach
– Peptides
• Cholecystokinen, obestatin
terminate meal
• Ghrelin stimulates the
appetite
– Changes in blood glucose or
amino acids
• May regulate carbohydrate and
protein intake
The set-point theory:
Feedback control of energy intake & expenditure
• Long-term mechanisms
• Role of leptin
– Hypothalamus neurons
make neuropeptide Y
(NPY)
– NPY secretion
stimulates appetite
– Leptin is released from
adipose cells
– Leptin inhibits NPY
secretion
The set-point theory:
Feedback control of energy intake & expenditure
• Long-term mechanisms
• Role of leptin
– Increases in body fat will
increase leptin release,
decreasing the appetite
– Decreases in body fat
will decrease leptin
release, increasing the
appetite
• The development of
leptin resistance is
thought to be a cause
of obesity
The set-point theory:
Feedback control of energy intake & expenditure
• Long-term mechanisms
– An activity-stat has been proposed
– May involve secretion of dopamine in the brain
– Decreased energy expenditure will stimulate
physical activity
– Increased energy expenditure will induce physical
inactivity
How is fat deposited in the body?
• Hyperplasia of adipose cells
– Increase in number of adipose (fat) cells
– May be important in childhood obesity
– Appears to occur throughout life
• Hypertrophy of adipose cells
– Increase in amount of fat per adipose cell
– Maximal amount appears to be 1 mcg of fat per adipocyte
• May be a genetic predisposition to more adipose
cells
What is the cause of obesity?
• The simple answer
– Energy intake exceeds
energy expenditure
• The difficult answer
– Involves a complex
interplay of both genetic
and environmental
factors
Genetic factors
• Heredity is an important factor in etiology of obesity
– Studies with identical and fraternal twins
– Body composition of children related more to biological
parents as compared to adoptive parents
Genetic factors
• Obesity genes have been identified; over 340 in the
Human Obesity Gene Map
– Abnormalities in neural function leading to increase
energy intake; neural tracts that are difficult to change
– Decrease protein receptors for leptin; leptin resistance
may develop, thus NPY continues to stimulate the
appetite
Genetic factors in weight gain
• Human Obesity Gene Map
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–
–
–
–
–
–
–
A predisposition to sweet, high-fat foods
Impaired function of hormones such as insulin
Decreased levels of human growth hormone
Low plasma leptin concentrations
Greater number of fat cells
An enhanced metabolic efficiency in storing fat
A lower resting energy expenditure (REE)
Lower levels of spontaneous physical activity, or NEAT,
during the day
– Lower levels of energy expenditure during light exercise
Environmental factors
• Environmental factors also highly involved in the
development of obesity
• “The marked increase in obesity worldwide appears
to be attributable to a modern society that explicitly
encourages the consumption of supersized portions
of high-fat, high-sugar foods while implicitly
discouraging physical activity.
Thomas Wadden
University of Pennsylvania
Environmental factors in weight gain
• High-fat, high-Calorie foods
– High-fat foods
• Fat is palatable
• More Calories per gram
• May encourage overconsumption; less suppression of
appetite
• Dietary fat may be stored more efficiently than
carbohydrate or protein
Environmental factors in weight gain
• Fast foods
– High palatability
– High-fat content
– High-sugar content
– High energy density
Environmental factors in weight gain
• Low-fat, large-portion size, high-Calorie foods
– Liquid Calories
– 12-ounce bottle of sugar-sweetened soda
• 10 teaspoons of sugar; 150 Calories
• 20-ounce bottle; 250 Calories
– Sodas and other sugar flavored drinks thought to
underlie increase rate of obesity in children
– Average American consumes 300 more Calories
today than 15 years ago, mainly from
carbohydrates
Environmental factors in weight gain
• Physical inactivity and NEAT
– Technological advances may decrease activities of daily
living
– Decreasing levels of physical activity can contribute to
weight gain
– One study with NEAT found that mildly overweight
individuals stayed seated about 2.5 hours longer per day
than lean individuals
• Calculated this could lead to 350 fewer Calories expended per day
– Levine notes that NEAT may vary as much as 2,000 Calories
per day among different individuals
Environmental factors in weight gain
Other factors
• Sleep
– Reduced amount of sleep has been associated with
overweight and obesity
– More tired and less likely to exercise
– More chances to eat
– Being overweight may cause sleep apnea
• Emotional stress
– Perceived as an emergency; body eats more and stores fat
– Cortisol may stimulate caloric intake and deposit fat in
intra-abdominal fat depots
Environmental factors in weight gain
Other factors
• Personal relationships
– Research suggests social and family relationships may
contribute to weight gain
• Study of 12,000 subjects over 32 years
– Person’s chances of becoming obese increased by 57% if a
close friend became obese in a given time frame
– Similar findings with siblings and spouses
Environmental factors in weight gain
Other factors
• Drugs
– Alcohol
• Rich in Calories (7 per gram)
• Excess is stored as fat
• Alcohol intake does not suppress appetite or fat intake
– Nicotine
• May inhibit the appetite and increase REE
• Cessation of smoking may lead to weight gain
• Gain 11-13 pounds in 2 years
Interaction of Genetics and Environment
• Genes may be an important determinant of weight
gain, but do not explain the rapid increase in obesity
over the course of the past 20 years
• Environmental factors are more important, such as
changes in lifestyle
– The “Freshman Fifteen” not quite that high, but more
likely the “Freshman Five”
• Creeping obesity
– 100 Calories extra per day = 10 extra pounds per year
– 200 Calories extra per day = 20 extra pounds per year
Figure 10.7
Can the set point change?
• The settling-point theory
– Weight gain
• Genes may increase leptin resistance
• Body weight increases to new level
– Weight loss
• Resting metabolism may return to normal after initial
decrease
– Prevention may be the key to weight gain and
obesity
Why is prevention of
childhood obesity so important?
• Current 16 % of overweight children will ↑ to 24% by 2015
• Neural circuits predisposing to obesity developed while young
are not easily abolished
– Obesity persists from preschool through elementary school and into
young adolescence
• Diet is a key factor in childhood obesity
– Sugar-sweetened beverages
• Physical inactivity
– Television viewing and similar sedentary behaviors
• Physical inactivity and diet
– Children consume more Calories when watching TV
Weight Gain, Obesity, and Health
• Obesity may impair health in several ways
1. Increased mass of adipose tissue places strain on body
tissues, such as the heart and joints
2. Increased number of adipose cells may secrete more
adipokines, which may induce pathogenic processes such
as inflammation
3. Adipose cells may convert androgen hormones to
estrogen hormones, which may affect cellular processes
What health problems are associated with
overweight an obesity?
• Health costs of obesity may parallel those
associated with cigarette smoking
• $100 billion is estimated health costs of
obesity-related health problems
– 5-10 % of annual health care costs
Possible health problems associated with
overweight an obesity
•
•
•
•
•
•
•
•
•
Asthma
Cancer
Cardiovascular disease
Diabetes (type 2)
Dyslipidaemia
Gallstones
Gastrointestinal reflux
Gout
Hypertension
• Insulin resistance
• Low self-image and
self-esteem
• Osteoarthritis
• Respiratory dysfunction
• Sleep apnea
• Social disabilities
• Stroke
• Vertebral disk herniation
Obesity and cardiovascular disease
• American Heart Association
– Obesity is a major risk factor
– 1% ↑ in BM! ↑ CHD risk by 5% - 7%
• Role of adipokines for CHD
– Harmful adipokines may be ↑ in the obese
– Promote inflammation and clotting
• Excess body fat also promotes risk factors for CHD
– High blood pressure
– Hypercholesterolemia
– Type 2 diabetes
• Diabesity
Obesity and cancer
•
•
•
•
Obesity is a risk factor for certain cancers
May account for 14% of cases in men; 20% in women
Those with highest BMI (≥ 40) at greatest risk
Recent American Institute of Cancer Research worldwide report
found convincing evidence of a link between increased body
fatness and several cancers
–
–
–
–
–
Breast
Colorectum
Pancreas
Esophagus
Kidney
Obesity and maternal health
• Overweight and obesity are associated with
increased risk of stillbirth
– Recent meta-analysis of 9 studies
• OR of 1.47 in women who were overweight
• OR of 2.07 in women who were obese
Obesity:
Mortality, morbidity, and quality of life
• Overweight may increase risk of premature mortality,
but not as great as obesity
• Obesity may contribute to 300,000 deaths annually
in the United States
– BMI of 30-35 is high risk of death
– BMI > 35 accounts for largest majority of deaths
• Projected years of life lost with severe obesity at ages
20-30
– White men: 13 years
– Black men: 20 years
White women: 8 years
Black women: 5 years
How does location of body fat affect
health?
• Regional fat distribution
– Android-type obesity
• Abdominal region
• Visceral fat
– Gynoid-type obesity
• Gluteal-femoral region
• Hips, buttocks, thighs
Android-type obesity
• Android-type fat cells (deep visceral fat cells)
– Release adipokines harmful to health
• Trigger inflammation and coagulation
• Induce insulin resistance (resistin)
– Decrease release of adiponectin, a protective
adipokine
• May lead to the metabolic syndrome
The Metabolic Syndrome
• Metabolic syndrome
– Cardiometabolic syndrome
– Syndrome X
• Cluster of symptoms
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–
–
–
–
–
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Hyperinsulinemia
Insulin resistance
Impaired glucose tolerance
Increased small, dense LDL-cholesterol
Decreased HDL-cholesterol
Hypertension
Increased plasma fibrinogen and clotting
The Metabolic Syndrome
• Increased risk of CHD and type 2 diabetes
• 25% of American adults have 3 or more components
of the metabolic syndrome
– Individuals with a normal (18.5-24.9) or overweight (25.029.9) BMI with high waist circumference may have several
of the components of the metabolic syndrome
The Metabolic Syndrome
• New classification system
• Waist circumference and two of four components
Men
Women
37
31.5
Elevated serum triglycerides (mg/dL)
150
150
Subnormal HDL-cholesterol (mg/dL)
< 40
< 50
130/85
130/85
100
100
Waist circumference (inches)
Elevated blood pressure (mmHg)
Elevated fasting blood sugar (mg/dL)
The Metabolic Syndrome
• Android-type obesity is a major risk factor for
mortality in both men and women
– Increased risk of CHD and cancer
– Even among normal-weight women
• However, weight loss via dieting and exercise appears
to preferentially decrease abdominal fat
– Small weight losses can reduce several of the risk factors in
the metabolic syndrome
Does being obese increase health risks in youth?
• Psychological problems
– May impair self-image and self-esteem
– May avoid physical activities and miss the socializing
aspects of play
• Physical health problems
– High blood pressure
– Type 2 diabetes
– May lead to health problems
in early adulthood
Does losing excess body fat reduce health
risks and improve health status?
• Weight loss is one of the major recommendations of
health professionals as a means to enhance health
– American Heart Association
– American Institute of Cancer Research
– American Diabetes Association
• Diet plans
– The DASH diet
– The OmniHeart diet
Does being physically fit negate the adverse
health effects associated with being overweight?
• Some scientists contend that being overweight does
not increase risk of mortality if various risk factors,
such as blood pressure and serum lipids, are normal
• Increased physical activity may reduce various risk
factors even though weight is not lost
– Increase insulin sensitivity
– Decrease blood pressure
– Increase self-esteem
• However, benefits of exercise work best when excess
body fat is lost
Fitness and Fatness
Unfit and
Fat
Unfit and
Not fat
Fit and
Fat
Fit and
Not Fat
•Highest mortality rate
•Lower mortality rate
•Lower mortality rate
•Lowest mortality rate
Active at Any Size
Weight Control Information Network
www.win.niddk.nih.gov
• Click on “Publications for the Public” to access Active
at any Size, a program to help encourage and help
overweight individuals plan an exercise program.
Excessive Weight Loss and Health
What health problems are associated with
improper weight-loss programs and practices?
• Weight loss: Health; Appearance; Sport performance
• Improper weight-control programs
–
–
–
–
–
–
Dehydration
Weight-loss dietary supplements
Weight-loss drugs
Very-low-Calorie diets
Weight cycling
Young athletes
Dehydration
• Excessive dehydration
–
–
–
–
Exercise
Sauna
Diuretics and laxatives
Possible heat illnesses
• Case study with bodybuilders
– Diuretics and potassium supplements
– Hyperkalemia maybe fatal
Weight-loss Dietary Supplements
• Numerous over-the-counter (OTC) products
– Lose 30 Pounds in 30 Days
• Most OTC weight-loss supplements do not appear to
be effective
• More research needed with some
– Pyruvate and CLA
• Some herbals may be dangerous
– Ephedra
– Others associated with liver damage
Weight-loss Drugs
• Available for use in the United States
– Sibutramine (Meridia)
• Inhibits uptake of neurotransmitters; suppresses appetite
• Stimulate thermogenesis
– Orlistat (Xenical)
• Block gastric lipases; inhibit fat absorption
• alli (OTC version)
• Europe
– Rimonabant (Acomplia)
• Suppresses the appetite
• Nicotine patches may help prevent weight gain with smoking
cessation
• Drug use optimal when used with lifestyle changes
Very-Low-Calorie Diets (VLCDs)
• Modified fasts
– < 800 Calories per day
– May be successful under medical supervision
– Used as a first step in weight-loss programs
• Possible problems
– Weakness
– Loss of libido
– Decreased blood volume
Constipation
Decreased HDL
Cardiac arrhythmias
• Best when coupled with lifestyle changes
Weight cycling
• The Yo-Yo syndrome
– VLCD followed by high-Calorie diet
– Cycles of weight loss followed by weight gain
• Previous research suggested
– May lead to decrease in REE
– Weight gain may contain more fat, less muscle
• Current research reveals
– No adverse effects of weight cycling
• Weight gain does not exceed weight loss
• More research needed to explore health effects
Young athletes
• Making weight for sports
– Possible inadequate intake
• Protein
• Iron, calcium, zinc
– Possible effects of a combination of intense training and
insufficient energy intake
• Inhibition of hypothalamus and pituitary gland
• Suppressed sexual development
• Restricted growth
– ACSM: Does not appear to affect growth in wrestlers
– May pose a problem in young female gymnasts
What are the major eating disorders?
• Disordered eating
– Less severe than full fledged Eating Disorders
– American Psychiatric Association (APA)
• Eating Disorders Not Otherwise Specified (EDNOS)
– Purging disorders
• Eating disorders (APA)
– Anorexia nervosa (AN)
– Bulimia nervosa (BN)
– Binge eating disorder (BED)
Anorexia nervosa (AN)
• Compulsive personality disorder
– Not completely understood
• Strong genetic predisposition
– Identical and fraternal twin studies
– Genes may be linked to appetite control
APA Criteria for Anorexia nervosa
• Refusal
to maintain body
weight over a minimal
normal weight for age and
height
• An intense fear of gaining
weight or becoming fat,
even though underweight
• A disturbance in the way
one’s body weight or shape
is perceived
• Amenorrhea, or the absence
of at least three consecutive
menstrual cycles in
normally menstruating
females.
Anorexia nervosa
• Prevalence is relatively low
– Primarily females under the age of 25
– 1% or less of the general population
– As high as 2% in college students
• Strong genetic predisposition
– Identical and fraternal twin studies
• Chronic low self-esteem
• Serious medical consequences
– Anemia
– Decreased heart mass
– High risk for suicide
Anorexia nervosa
• Therapy for AN may
require hospitalization
and intensive
psychiatric treatment
for both the patient and
family
• The outcome for
females with AN has
changed little over the
past 50 years
• Mortality is high
– AN with lowest body
weight at highest risk
APA Criteria for Bulimia nervosa (BN)
• Recurrent episodes of binge eating, at least two per
week for 3 months.
• Lack of control over eating during the binge.
• Regular use of self-induced vomiting, laxatives,
diuretics, fasting, or excessive exercise to control
body weight.
• Persistent concern with body weight and body shape.
Diagnostic and statistical manual of mental disorders (Fourth edition)
Bulimia nervosa
• Bulimia nervosa means morbid hunger
– Loss of control over the impulse to binge
– Binge-purge syndrome
• BN is more common than AN
– 2-3% of the general population
– One estimate suggests up to 10% of college students
• Medical consequences of vomiting and laxatives
– Erosion of tooth enamel
– Tears in esophagus
– Electrolyte imbalances
• Psychological counseling may help; Prozac use has
been approved
APA Criteria for Binge Eating Disorder (BED)
•
•
•
•
•
Eat more quickly than usual during binge episodes
Eat until they are uncomfortably full
Eat when they are not hungry
Eat alone because of embarrassment
Feel disgusted, depressed, or guilty after eating
Binge Eating Disorder (BED)
• Individuals with BED have behaviors common to BN,
but do not purge
• Health consequences include
– Weight gain and obesity
– Increased risk of CHD and cancer
• Treatment is similar to BN
What eating problems are associated with sports?
• Eating Disorders Not Otherwise Specified
• Anorexia Athletica
• Weight loss as an ergogenic aid
– Wrestling
– Gymnastics
– Cheerleading
– Bodybuilding
– Lightweight football and rowing
– Distance running
Anorexia Athletica
Five set criteria
Additional criteria (1 or more)
• Excessive fear of becoming
obese
• Restriction of caloric intake
• Weight loss
• No medical disorder to
explain leanness
• Gastrointestinal complaints
•
•
•
•
•
•
Disturbance in body image
Compulsive exercising
Binge eating
Use of purging methods
Delayed puberty
Menstrual dysfunction
Eating disorders in sports
• Estimates of prevalence vary
– NCAA study
• 20-40 % of female college athletes may exhibit criteria
of eating disorders
• 50-70 % in certain sports, such as gymnastics
– One study of NCAA Division I athletes
• 10% with symptoms of bulimia nervosa
• 3% with symptoms of anorexia nervosa
• Symptoms of eating disorders may abate at the end
of the competitive season
The Female Athlete Triad
The Female Athlete Triad
• Disordered eating
– Low energy availability
• Amenorrhea
– Disturbance of hypothalamus-pituitary-ovary axis
– Primary or secondary
• 3-6 months or more between periods
• Osteoporosis
– Decreased estrogen from the ovaries
– Low body fat so less conversion of androgens to estrogen
– Estrogen is involved in bone metabolism
The Female Athlete Triad
• Prevention involves education of those involved sports
– Coaches, athletic trainers, administrator, parents
• What to look for
–
–
–
–
–
Unexplained weight losses
Frequent weight fluctuations
Sudden increases in training volume
Excessive concern with body weight
Appearance, and evidence of bizarre eating practices
The Female Athlete Triad
• Treatment
– Counsel with the athlete
– Increase dietary energy intake
– Decrease exercise-associated energy expenditure
• Mental health practitioners may be needed for
athletes with eating disorders
Body Composition and Physical
Performance
Weight control as an ergogenic aid
What effect does excess body weight have
on physical performance?
• Excess body weight as fat or muscle
– Disadvantages
– Advantages
• Lose fat weight
– Enhance energy efficiency
– Improve appearance
• Gain muscle weight
– Increase power
– Increase stability
– Improve appearance
Excess body weight & physical performance
• Adverse effects of excess body fat or muscle mass
– May impair energy efficiency
– May detract from aesthetic appearance
Excess body weight & physical performance
• Beneficial effects of excess body fat or muscle mass
– May increase strength and power
– May increase stability
– May enhance aesthetic appearance
Weight Control for Performance
• Loss of excess body fat
– In general, a 1% loss of excess body fat will increase
running speed by 1% (Craig Dean, Running Times)
– Example:
• Current 10K race pace is 8:00/mile, or 49:36
• Lose 5% of excess body fat
• Increase 10K race pace speed to 7:36/mile
– 8:00 (480 sec) x .05 = 24 sec; 8:00 – 0:24 = 7:36
– New 10K time is about 47:12
• Comparable improvements in the marathon (3:29:36 improves to
3:19:08) or 10 minutes faster
Body weight loss and physical
performance
• Weight loss should be fat, not muscle involved in
energy production
• Recall the limitations of body fat measurements as a
means to predict body fat levels for sports
performance
– May lead to excess weight loss and impaired performance
• Keep in mind that body composition is only one
factor impacting sport performance
Does excessive weight loss impair physical
performance?
• Improper weight-loss programs may impair
performance
– Excessive dehydration
– Diuretics and laxatives
– Starvation-type diets
• Proper weight-loss programs
–
–
–
–
Lose weight, mainly fat, gradually
Prevent hypoglycemia
Prevent dehydration
Maintain lean body mass, or muscle