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Chapter 10Weight Control

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 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

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

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

Body fat percentage

• Recommendations for health /performance vary

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

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

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

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

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

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

• 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

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