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Unit 5

Body Composition and Weight Management

Body Fat?

Fat Facts & Myths

• Economic cost of obesity=$39 billion/year
• Genetic factors=25% of variability in body fat in population
• Genetic factors account for where you “wear your fat”
• Spot reducing?
• Cellulite?
• Freshman 10, 15, 20, 40?

Body Composition

Lean and Fat Compartments

• Lean compartment
  • muscles, skeleton, organs, (water)
• Fat compartment
  • essential fat: structural & functional
  • storage fat: energy reservoir
  • - most located in adipose tissue

The Development of Body Fat

Adipose tissue contains billions of fat cells

• Hyperplastic obesity
  • results from excessive number of fat cells, typically during growth, youth-onset
• Hypertrophic obesity
  • results from enlargement of fat cells, adult onset

Norms for Body Composition

Males and females have similar amounts of storage fat, but differ in the amount of essential fat they possess

Body Image

• At any one time, what percent of American women are dieting to lose weight?
  • 50% (HS girls=60%)
• How about men?
  • 25% (HS boys=24%)
• How many of those are actually overweight, more or less, for women? For men? Why?

Unhealthy Responses to Body Composition/ Body Shape

Unhealthy eating patterns to control body weight/shape:

• Normal vs. Dysfunctional Eating
  • regular vs. irregular chaotic eating
• eating for nourishment & health vs. eating for body image, anxiety, boredom, etc.
• regulated by hunger vs. regulated by will power, calories planned, emotions, guilt
• small children & those who don’t diet vs. girls & women in the U.S.
• Anorexia Nervosa
  • self starvation & intense fear of fatness
  • 1% of population is anorexic, 90% female
• Bulimia Nervosa
  • uncontrolled binge eating followed by purging (vomiting, laxatives, exercise) behavior
  • 1 in 5 college-age women
  • symptoms: chronic sore throat, tooth enamel decay, swollen glands & face
• Binge Eating
  • binging without purging
• Supplementation & Ergogenic Aids
  • creatine
  • steroids
• Fad Diets
  • ex. high protein, low carbohydrate
  • diet

Muscle Dysmorphia

Muscle dysmorphia is a preoccupation with body size.  Individuals (usually men) with this condition believe that their bodies are small and underdeveloped when actually they are usually quite muscular and large due to the controlling behavior they are preoccupied with carrying out in order to build-up this "puny" body.  The behavior they engage in includes diet and exercise and a strong focus on body fat.  This behavior is often at the expense of relationships and employment.

 Pope, et al. (1999) conducted a study that examined the development of action figures or male dolls from the early GI Joe dolls and original Star Wars dolls through their evolution to today.  Each of the dolls pictured below is displayed next to its earlier model.  Clearly, the body shape and muscular definition has increased from the original model.  The researchers considered how young boys may view these dolls as a model for the ideal male body and as they develop and mature these young men strive to look muscular and "cut" as these dolls do.  This is not to say that action figures cause muscle dysmorphia, but to encourage us to look at how males are represented in the media, at various levels (comic strips, action figures, models, movie and sport stars), and how young boys and men internalize these cultural ideals which influence how they behave in order to control their bodies and ultimately how they feel about themselves. 

1.2.

3.4.

Pope et al. (1999)

Patterns of Body Fat Distribution

• Android pattern
  • accumulation of fat on the trunk
  • typically males
  • associated with increase risk of heart disease & diabetes
• Gynoid pattern
  • accumulation of fat on the limbs (hips & thighs)
  • typically females
  • after menopause, women move toward the android pattern

Assessing Body Composition

• Indirect methods
  • Height-weight tables
  • Body mass index
  • Skinfolds
  • Bioelectrical impedance
  • Dual-energy x-ray absorptiometry
  • Underwater weighing: “lab standard”
  • Bod Pod

Energy Balance

• Energy intake vs. energy expenditure
  • Caloric balance
    • energy intake = energy expenditure
  • Positive caloric balance
    • energy intake > energy expenditure
  • Negative caloric balance
    • energy intake < energy expenditure

Elements of Energy Balance

1. Basal metabolic rate (BMR)
   • energy the body uses while awake and at rest
   • about 60% of total daily energy expenditure
2. Physical activity
• about 30% of daily expenditure
• sitting up, walking, exercising
3. Thermic effects
   • food digestion, absorption, storage, thermoregulation
   • about 10% of daily expenditure

Achieving a Negative Caloric Balance

• Diet
  • energy intake < energy expenditure
• Exercise
  • energy intake < energy expenditure
• Diet plus exercise
  • energy intake < energy expenditure

Diet vs. Exercise

• Pitfalls of dieting
  • if intake is low,
  • can cause nutritional deficiency
  • slows BMR
  • correlation between “weight cycling” and health problems
• The importance of exercising
  • low energy expenditure (diet same, activity less) is the primary cause of weight gain
  • exercise increases BMR and fat utilization
  • many positive health benefits

Designing an Exercise Program for Weight Loss

• Choice of exercise
  • aerobics and weight training
• Intensity
  • lower intensities utilize fat, but higher intensities burn calories faster
• Frequency & Duration
  • emphasize caloric expenditure
  • gradually increase frequency to 5-7 days/week
  • 1 lb. of fat = 3500 kcals so, 500kcals saved per day = 1 lb loss/week

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