1. Body Composition Chapter 18

2. Methods of Determining If an Individual Is Obese Metropolitan Life Insurance Company’s height/weight tables –Percentage above recommended weight Body mass index (BMI) Problems w/ these methods

3. Body Composition Measurement Total body water (TBW) –Isotope dilution –Bioelectrical impedance analysis (BIA) Bone density –Photon absorptiometry Lean tissue mass –Potassium-40 Whole body Density –Underwater weighing Thickness of various tissues –Skinfolds –Ultrasound –Radiography

4. Models of Body Composition 2-component 3-component 4-component

5. The 2-component Model Underwater weighing –Based on D b –Use equation to convert D b to %fat based on age, gender & race Skinfolds –Thickness of subcutaneous fat is measured

6. Underwater Weighing

7. Body Fatness for Health & Fitness Recommended BF –Males –Females Health concerns

8. Obesity As a Risk Factor Primary contributing factor Secondary contributing factor –Endometrial cancer Associated w/ (not caused by obesity)

9. Obesity: Definition & Prevalence Definition –Men –Women Prevalence in U.S.

10. Obesity: Benefits of Weight Loss Obesity is associated w/: If everyone achieved optimal weight

11. Obesity: Fat Cell Size vs. # 25 billion fat cells in normal-weight individual

12. Obesity: Fat Cell Size & #

13. Obesity: Genetic & Cultural Factors Genetic factors Cultural factors

14. Set Point & Obesity The tendency of an individual to return to a certain weight following weight loss suggests there is a biological set point for body weight Physiological set point model Cognitive set point model

15. Physiological Set Point

16. Energy Balance Static energy balance Dynamic energy balance ∆ of energy stores energy intake energy expenditure = - rate of ∆ of energy stores rate of ∆ of energy intake rate of ∆ of energy expenditure = -

17. Nutrient Balance CHO & PRO Fat

18. The Food Quotient Food quotient (FQ) Respiratory quotient (RQ)

19. The FQ, RQ & Nutrient Balance RQ = FQ RQ > FQ RQ < FQ

20. Diet & Weight Control Diets high in fat are linked to obesity Calories count & must be considered!

21. Basal Metabolic Rate (BMR) Rate of EE under standardized conditions Represents 60-75% total EE Reduced in response to reduced caloric intake (dieting or fasting)

22. Thermogenesis “Heat generation” associated w/: –Ingestion of meals (thermic effect of feeding) –Brown adipose tissue –“Futile cycles” Metabolic cycles (NA + /K + pump activity)

23. Physical Activity

24. Effect of Exercise on Appetite Most humans

25. Exercise & Body Composition Individuals who exercise generally have lower body weight & %fat Weight loss in conjunction w/ exercise

26. Weight Loss vs. Weight Maintenance Weight loss Weight maintenance –Light to moderate exercise –Moderate exercise –Vigorous exercise

27. Diet, Exercise, & Weight Control Energy and nutrient balance is more easily achieved on a low fat diet Exercise  s the chance that energy balance will be achieved Exercise promotes health-related benefits –  d fitness, HDL cholesterol