Energy Balance and Body Composition

1. Energy Balance and Body Composition Studying = 1 or 2 kcalories/minute

2. Energy Balance • unbalanced energy • excessive body fat • deficient body fat • periodic refueling • 3,500 kcal = 1# fat • reserves 50,000 – 200,000 kicalories

3. Energy Balance • rapid gain or loss • fat, lots of fluid, lean tissue • gradual loss or gain • 75 % fat, 25% lean tissue

4. Food Composition • bomb calorimeter • mathematical computation • 4 kcal/1 gram carb • 4 kcal/1 gram protein • 9 kcal/1 gram lipid

5. Food Intake • hunger • physiological need triggers messengers from hypothalamus • influenced by • nutrients in blood • preceding meal • eating patterns • climate • exercise • hormones • illness

6. Food Intake • appetite • sight and smell • also initiates eating

7. Food Intake • satiation • feeling of fullness • stop eating • satiety • continues to suppress hunger

8. Food Intake

9. Food Intake • overriding hunger and satiety • cravings • bored • stress • time of day • disease

10. Food Intake • sustaining satiety • food composition plays a role • protein is most satiating • ability to suppress hunger • fat is least satiating • stimulates appetite • energy dense

11. Food Intake • Sustaining satiation and satiety • lower-fat foods can be eaten in larger portions for the same number of kcalories

12. Food Intake • hypothalamus • control center • message coordinator • neuropeptide Y • causes carb cravings • initiates eating • energy • fat storage

13. Energy Out Physical activities Thermic effect of food Basal metabolism • body breaks down carbs, fats, proteins • generates heat • thermogenesis • measured 3 ways • basal metabolism • physical activity • food consumption

14. Basal Metabolism • BMR: basal metabolic rate • energy used for body temp, breathing, heart beating, filtering wastes, etc. • 60-65% • heavier weight means higher BMR • not proportional to body weight

16. Physical Activity • voluntary movement • most variable • most changeable • influences weight gain and loss • energy needed is dependent on • muscle mass • body weight • activity • duration, frequency, intensity

17. Thermic Effect of Food: TEF • acceleration of activity when eating • > for high protein foods • > if eaten all at once • usually ignored • adaptive thermogenesis • adapting to changes in circumstances

18. Energy Requirement Estimation • gender • growth • age • physical activity • body composition • body size

19. Body Weight • body weight = fat + lean tissue + water • fashion • self acceptance • health concerns • overweight • diabetes, hypertension, some cancers, heart disease, osteoarthritis

20. Body Mass Index: BMI • measure of weight and height, not body composition • healthy: 18.5 – 24.9 • underweight: less than 18.5 • overweight: above 25 • obese: above 30 United States

21. BMI Values Used to Assess Weight 18.5 25 30 6'6" 6’5" 6’4" 6’3" Underweight Healthy Overweight Obese 6’2" 6’1" 6’0" 5’11" 5’10" 5’9" 5’8" 5’7" 5'6" 5’5" 5’4" 5’3" Key: 5’2" BMI <18.5 = underweight 5’1" BMI 18.5 to 24.9 = healthy 5’0" BMI 25.0 to 29.9 = overweight BMI >_30 = obese 4’11" 4’10" 50 75 100 125 150 175 200 225 250 275 Pounds (without clothes)

22. Body Fat Distribution • central obesity • heart disease, stroke, diabetes, hypertension • lower body fat • relatively harmless

23. Methods Used to Assess Body Fat

24. Health Risks • underweight • malnutrition • wasting diseases • infertility • birth to unhealthy babies • osteoporosis • overweight • diabetes, heart disease, etc

25. active yet overweight BMI = 36 obese 6’3” 245 pounds overweight? overfat? BMI = 30