Energy Balance and Weight Control

1. Energy Balance and Weight Control

3. Obesity is a Growing Problem • 127 million adults in the U.S. are overweight, 60 million obese, and 9 million severely obese. • 64.5 percent of U.S. adults are overweight (BMI≥25) • 30.5 percent are obese (BMI≥30) • 4.7 percent are severely obese (BM≥40)

4. Obesity Trends* Among U.S. AdultsBRFSS, 1985 Source: Mokdad A H, et al. J Am Med Assoc1999;282:16, 2001;286:10.

5. Obesity Trends* Among U.S. AdultsBRFSS, 2001 Source: Mokdad A H, et al. J Am Med Assoc1999;282:16, 2001;286:10.

6. Prevalence of Obesity in Ohio

7. Obesity: A Major Health Issue • Obesity is the No. 2 preventable cause of death and disability (smoking is #1) • Obesity is associated with increased risk of heart disease, stroke, gallbladder disease, cancer, osteoarthritis, sleep apnea • Obesity-related health problems cost $75 billion annually (2003 data) • The public pays about $39 billion a year -- or about $175 per person -- for obesity through Medicare and Medicaid programs

8. Health Risks of Obesity • Cardiovascular disease • Cancer • Hypertension • Bone/joint disorders • Type 2 diabetes

9. Energy Balance Relationship between energy intake and energy expended • Positive energy balance • Energy intake > energy expended • Results in weight gain • Negative energy balance • Energy intake < energy expended • Results in weight loss

10. Estimating Kcal Content in Food • Bomb calorimeter • Burns food inside a chamber surrounded by water • Heat is given off as food is burned • The increase in water temperature indicates the amount of energy in the food

11. Use and Storage of Fat • Most fat is stored directly into adipose tissue • Body has unlimited ability to store fat (as fat) • Fat will remain as fat for storage • Physical activity encourages the burning of dietary fat

12. Use and Storage of CHO • Limited CHO can be stored as glycogen • Most CHO is used as a energy source to meet immediate energy needs • Excessive CHO will be converted to fat (for storage) • Body prefers to use CHO as energy source • Only excess intake of CHO and protein will be turned into fat

13. Use and Storage of Protein • Protein is primarily used for tissue synthesis • Excess protein is used for energy • Some protein will be synthesized into fat (for storage) • Protein cannot be stored as protein

14. Energy In Vs. Energy Out NEAT Basal Metabolism Dietary Intake Physical Activity Thermic Effect of food

15. Basal Metabolism • The minimum energy expended to keep a resting, awake body alive • ~60-70% of the total energy needs • Includes energy needed for maintaining a heartbeat, respiration, body temperature • Amount of energy needed varies between individuals • Approximately 0.9 kcal/kg/hr

16. Estimate Basal Metabolism Female: Wt (kg) x 0.9 kcals/hour x 24 50 kg (110 lb) x 0.9 x 24 = 1080 kcals Male: Wt (kg) x 1 kcal/hour x 24 100 kg (220 lb) x 1 x 24 = 2400 kcals

17. Calculate Your BMR ________ x ______ x 24 = ____ kcals/day This is only an estimate!!

18. Factors that Increase Basal Metabolism • Body surface area (weight, height) • Male gender • Body temperature • Thyroid hormone • Nervous system activity • Kcal intake • Pregnancy • Use of caffeine and tobacco

19. Factors that Decrease Basal Metabolism • Age • – 2% drop each decade after 30 • Low calorie diet • 10-20% decrease

20. Physical Activity • Increases energy expenditure beyond BMR • Varies widely among individuals • More activity, more energy burned • Lack of activity is the major cause of obesity

21. Thermic Effect of Food (TEF) • Energy used to digest, absorb, and metabolize food nutrients • “Sales tax” of total energy consumed • ~5-10% above the total energy consumed • TEF is higher for CHO and protein than fat • Less energy is used to transfer dietary fat into adipose stores

22. Nonexercise Activity Thermogenesis (NEAT) • Nonvoluntary physical activity triggered by overeating • Fidgeting • Maintenance of muscle tone • Maintenance of posture • Overeating increases sympathetic nervous system activity • Resists weight gain

23. Measurement of Body’s Energy Needs • Direct calorimetry • Measures heat output from the body using an insulated chamber • Expensive and complex • Indirect calorimetry • Measures the amount of oxygen a person uses • A relationship exists between the body’s use of energy and oxygen

24. Food Guide Pyramid Energy Estimates • 1600 kcals – sedentary women, some older adults • 2200 kcals – Children, teen girls, active women, most men • 2800 kcals – teen boys, active men, very active women

25. Food Guide Pyramid Calorie Estimates • Sedentary: 25-30 kcal/kg • Moderate activity: 35 kcal/kg • Heavy activity: 40 kcal/kg

26. Energy Needs from US Dietary Guidelines

27. What is a Healthy Body Weight? • Based on how you feel, weight history, fat distribution, family history of obesity-related disease, current health status, and lifestyle • Current height/weight standards only provide guides

28. A Healthy Body Weight • What is the lowest weight maintained for more than a year as an adult? • What weight was maintained without constantly feeling hungry? • Establish a “personal” healthy weight

29. Body Mass Index (BMI) • The preferred weight-for-height standard • Calculation: Body wt (in kg) OR Body wt (in lbs) x 703.1 [Ht (in m)]2 [Ht (in inches)]2 Health risks increase when BMI is > 25

30. BMI is Not a Measure of Body Fatness Height 6'3" Height 6'3" Weight 220 lbs Weight 220 lbs BMI 27.5 BMI 27.5

31. BMI Does Not Measure Body Fat • However, most people with high BMIs are overfat

32. BMI and Health

33. Overweight (BMI 25-30) Monitor for • Hypertension • Elevated LDL-cholesterol • Family history of obesity, CVD, certain cancers • Pattern of fat distribution • Elevated blood glucose: diabetes, insulin resistance

34. Perspective on Weight • Unrealistic goals • Listen to body’s cues (for hunger) • Eat a healthy diet • Physical activity • “Size acceptance”

35. Obesity • Excessive amount of body fat • Women with > 35% body fat • Men with > 25% body fat • Increased risk for health problems • Are usually overweight, but can have healthy BMI and high % fat • Measurements using calipers

36. Estimation of Body Fat • Underwater weighing Most accurate • Fat is less dense than lean tissue • Fat floats • Problems with • Children • Elderly • Very large • Fear of water

37. Estimation of Body Fat • Bioelectrical impedance • Low-energy current to the body that measures the resistance of electrical flow • Fat is resistant to electrical flow; the more the resistance, the more body fat you have • DEXA (dual x-ray photon absorptiometry) • An X-ray body scan that allows for the determination of body fat • Infrared light • Assess the interaction of fat and protein in the arm muscle

38. Skinfold Thickness Accurate with • Training • Good calipers • Multiple sites • Multiple measurements

39. Surgical risk Lung (pulmonary) disease Sleep apnea HTN CVD Bone and joint disorders (gout, osteoarthritis) Gallstones Cancers (breast, colon, pancreas, gallbladder) Infertility Pregnancy- difficult delivery Reduced agility Early death Health Problems Associated with Excess Body Fat

40. Desirable % Body Fat • Men: 8-25% • Women 20-35%

41. Body Fat Distribution Upper-body (android) obesity--apple shape • Associated with more heart disease, HTN, Type II Diabetes • Abdominal fat is released right into the liver • Encouraged by testosterone and excessive alcohol intake • Defined as waist measurement of > 40” for men and >35” for women

42. Body Fat Distribution

43. Body Fat Distribution Lower-body (gynecoid) obesity--Pear shape • Encouraged by estrogen and progesterone • After menopause, upper-body obesity appears • Less health risk than upper-body obesity

44. Juvenile-Onset Obesity • Develops in infancy or childhood • Increase in the number of adipose cells • Adipose cells have long lifespan and need to store fat • Makes it difficult to lose the fat (weight loss)

45. Adult-Onset Obesity • Develops in adulthood • Fewer (numbers of) adipose cells • These adipose cells are larger (store excess amount of fat) • If weight gain continues, the number of adipose cells can increase

46. Causes of Obesity Nature vs Nurture • Identical twins raised apart have similar weights • Genetics account for ~40%-70% of weight differences • Genes affect metabolic rate, fuel use, brain chemistry, body shape • Thrifty metabolism gene allows for more fat storage to protect against famine

47. Nature vs Nurture Obesity tends to run in families • If both parents are normal weight – 10% chance of obesity in offspring • If one parent is obese – 40% chance • If both parents obese – 80% chance Is it genetics or learned eating behavior?

48. Causes of Obesity Nurture debate • Environmental factors influence weight • Learned eating habits • Activity factor (or lack of) • Poverty and obesity • Female obesity is rooted in childhood obesity • Male obesity appears after age 30

49. Nature and Nurture • Obesity is nurture allowing nature to express itself • Location of fat is influenced by genetics • A child of obese parents must always be concerned about his weight

50. Nature and Nurture • The influence of environment is apparent in the fact that the prevalence of obesity has increased dramatically in the US in the past 40 years