2. 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
3. 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
4.
5. 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
6.
7.
8. Underwater weighing
• Hydrodensitometry
• Based on Archimedes’
principle
– Buoyancy of water
displacement
• Previously was the gold
standard
• SEM is about 2.0 - 2.5%
9. Air Displacement Plethysmography (APD)
• Based on air
displacement
• Advantages over
underwater weighing
• Reliable method in
testing same subject
over time
10. 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
11. 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
12. 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
13. Body mass index
• Screening for health
• Some classify a BMI of 35 or 40 as morbid obesity
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
15. 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
16. 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
17. 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
18. 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
19. 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 Constipation
– Loss of libido Decreased HDL
– Decreased blood volume Cardiac arrhythmias
• Best when coupled with lifestyle changes
20. 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)
21. Anorexia nervosa (AN)
• Compulsive personality disorder
– Not completely understood
• Strong genetic predisposition
– Identical and fraternal twin studies
– Genes may be linked to appetite control
22. 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.
23. 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
24. 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
25. 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)
26. 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
27. 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
28. 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
29. 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
30. Anorexia Athletica
Five set criteria
• Excessive fear of becoming
obese
• Restriction of caloric intake
• Weight loss
• No medical disorder to
explain leanness
• Gastrointestinal complaints
Additional criteria (1 or more)
• Disturbance in body image
• Compulsive exercising
• Binge eating
• Use of purging methods
• Delayed puberty
• Menstrual dysfunction
31. 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
34. 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
35. 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
36. 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
