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Energy Balance


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Energy Balance

  1. 1. Energy Balance and Weight Control
  2. 3. Obesity is a Growing Problem <ul><li>127 million adults in the U.S. are overweight, 60 million obese, and 9 million severely obese. </li></ul><ul><li>64.5 percent of U.S. adults are overweight (BMI ≥ 25) </li></ul><ul><li>30.5 percent are obese (BMI ≥ 30) </li></ul><ul><li>4.7 percent are severely obese (BM ≥ 40) </li></ul>
  3. 4. Obesity Trends* Among U.S. Adults BRFSS, 1985 Source: Mokdad A H, et al. J Am Med Assoc 1999;282:16, 2001;286:10.
  4. 5. Obesity Trends* Among U.S. Adults BRFSS, 2001 Source: Mokdad A H, et al. J Am Med Assoc 1999;282:16, 2001;286:10.
  5. 6. Prevalence of Obesity in Ohio
  6. 7. Obesity: A Major Health Issue <ul><li>Obesity is the No. 2 preventable cause of death and disability (smoking is #1) </li></ul><ul><li>Obesity is associated with increased risk of heart disease, stroke, gallbladder disease, cancer, osteoarthritis, sleep apnea </li></ul><ul><li>Obesity-related health problems cost $75 billion annually (2003 data) </li></ul><ul><li>The public pays about $39 billion a year -- or about $175 per person -- for obesity through Medicare and Medicaid programs </li></ul>
  7. 8. Health Risks of Obesity <ul><li>Cardiovascular disease </li></ul><ul><li>Cancer </li></ul><ul><li>Hypertension </li></ul><ul><li>Bone/joint disorders </li></ul><ul><li>Type 2 diabetes </li></ul>
  8. 9. Energy Balance <ul><li>Relationship between energy intake and energy expended </li></ul><ul><li>Positive energy balance </li></ul><ul><ul><li>Energy intake > energy expended </li></ul></ul><ul><ul><li>Results in weight gain </li></ul></ul><ul><li>Negative energy balance </li></ul><ul><ul><li>Energy intake < energy expended </li></ul></ul><ul><ul><li>Results in weight loss </li></ul></ul>
  9. 10. Estimating Kcal Content in Food <ul><li>Bomb calorimeter </li></ul><ul><li>Burns food inside a chamber surrounded by water </li></ul><ul><li>Heat is given off as food is burned </li></ul><ul><li>The increase in water temperature indicates the amount of energy in the food </li></ul>
  10. 11. Use and Storage of Fat <ul><li>Most fat is stored directly into adipose tissue </li></ul><ul><li>Body has unlimited ability to store fat (as fat) </li></ul><ul><li>Fat will remain as fat for storage </li></ul><ul><li>Physical activity encourages the burning of dietary fat </li></ul>
  11. 12. Use and Storage of CHO <ul><li>Limited CHO can be stored as glycogen </li></ul><ul><li>Most CHO is used as a energy source to meet immediate energy needs </li></ul><ul><li>Excessive CHO will be converted to fat (for storage) </li></ul><ul><li>Body prefers to use CHO as energy source </li></ul><ul><li>Only excess intake of CHO and protein will be turned into fat </li></ul>
  12. 13. Use and Storage of Protein <ul><li>Protein is primarily used for tissue synthesis </li></ul><ul><li>Excess protein is used for energy </li></ul><ul><li>Some protein will be synthesized into fat (for storage) </li></ul><ul><li>Protein cannot be stored as protein </li></ul>
  13. 14. Energy In Vs. Energy Out NEAT Basal Metabolism Dietary Intake Physical Activity Thermic Effect of food
  14. 15. Basal Metabolism <ul><li>The minimum energy expended to keep a resting, awake body alive </li></ul><ul><li>~60-70% of the total energy needs </li></ul><ul><li>Includes energy needed for maintaining a heartbeat, respiration, body temperature </li></ul><ul><li>Amount of energy needed varies between individuals </li></ul><ul><li>Approximately 0.9 kcal/kg/hr </li></ul>
  15. 16. Estimate Basal Metabolism <ul><li>Female: Wt (kg) x 0.9 kcals/hour x 24 </li></ul><ul><li> 50 kg (110 lb) x 0.9 x 24 = 1080 kcals </li></ul><ul><li>Male: Wt (kg) x 1 kcal/hour x 24 </li></ul><ul><li>100 kg (220 lb) x 1 x 24 = </li></ul><ul><li> 2400 kcals </li></ul>
  16. 17. Calculate Your BMR <ul><li>________ x ______ x 24 </li></ul><ul><li>= ____ kcals/day </li></ul><ul><li>This is only an estimate!! </li></ul>
  17. 18. Factors that Increase Basal Metabolism <ul><li>Body surface area (weight, height) </li></ul><ul><li>Male gender </li></ul><ul><li>Body temperature </li></ul><ul><li>Thyroid hormone </li></ul><ul><li>Nervous system activity </li></ul><ul><li>Kcal intake </li></ul><ul><li>Pregnancy </li></ul><ul><li>Use of caffeine and tobacco </li></ul>
  18. 19. Factors that Decrease Basal Metabolism <ul><li>Age </li></ul><ul><ul><li>– 2% drop each decade after 30 </li></ul></ul><ul><li>Low calorie diet </li></ul><ul><ul><li>10-20% decrease </li></ul></ul>
  19. 20. Physical Activity <ul><li>Increases energy expenditure beyond BMR </li></ul><ul><li>Varies widely among individuals </li></ul><ul><li>More activity, more energy burned </li></ul><ul><li>Lack of activity is the major cause of obesity </li></ul>
  20. 21. Thermic Effect of Food (TEF) <ul><li>Energy used to digest, absorb, and metabolize food nutrients </li></ul><ul><li>“Sales tax” of total energy consumed </li></ul><ul><li>~5-10% above the total energy consumed </li></ul><ul><li>TEF is higher for CHO and protein than fat </li></ul><ul><li>Less energy is used to transfer dietary fat into adipose stores </li></ul>
  21. 22. Nonexercise Activity Thermogenesis (NEAT) <ul><li>Nonvoluntary physical activity triggered by overeating </li></ul><ul><li>Fidgeting </li></ul><ul><li>Maintenance of muscle tone </li></ul><ul><li>Maintenance of posture </li></ul><ul><li>Overeating increases sympathetic nervous system activity </li></ul><ul><li>Resists weight gain </li></ul>
  22. 23. Measurement of Body’s Energy Needs <ul><li>Direct calorimetry </li></ul><ul><ul><li>Measures heat output from the body using an insulated chamber </li></ul></ul><ul><ul><li>Expensive and complex </li></ul></ul><ul><li>Indirect calorimetry </li></ul><ul><ul><li>Measures the amount of oxygen a person uses </li></ul></ul><ul><ul><li>A relationship exists between the body’s use of energy and oxygen </li></ul></ul>
  23. 24. Food Guide Pyramid Energy Estimates <ul><li>1600 kcals – sedentary women, some older adults </li></ul><ul><li>2200 kcals – Children, teen girls, active women, most men </li></ul><ul><li>2800 kcals – teen boys, active men, very active women </li></ul>
  24. 25. Food Guide Pyramid Calorie Estimates <ul><li>Sedentary: 25-30 kcal/kg </li></ul><ul><li>Moderate activity: 35 kcal/kg </li></ul><ul><li>Heavy activity: 40 kcal/kg </li></ul>
  25. 26. Energy Needs from US Dietary Guidelines
  26. 27. What is a Healthy Body Weight? <ul><li>Based on how you feel, weight history, fat distribution, family history of obesity-related disease, current health status, and lifestyle </li></ul><ul><li>Current height/weight standards only provide guides </li></ul>
  27. 28. A Healthy Body Weight <ul><li>What is the lowest weight maintained for more than a year as an adult? </li></ul><ul><li>What weight was maintained without constantly feeling hungry? </li></ul><ul><li>Establish a “personal” healthy weight </li></ul>
  28. 29. Body Mass Index (BMI) <ul><li>The preferred weight-for-height standard </li></ul><ul><li>Calculation: </li></ul>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
  29. 30. BMI is Not a Measure of Body Fatness <ul><li>Height 6'3&quot; Height 6'3&quot; Weight 220 lbs Weight 220 lbs BMI 27.5 BMI 27.5 </li></ul>
  30. 31. BMI Does Not Measure Body Fat <ul><li>However, most people with high BMIs are overfat </li></ul>
  31. 32. BMI and Health Severely obese Major health risk 40.0 and above Obese Increased health risk 30.0 and Above Overweight Monitor for risk 25.0 – 29.9 Normal 18.5 – 24.9 Underweight Below 18.5
  32. 33. Overweight (BMI 25-30) Monitor for <ul><li>Hypertension </li></ul><ul><li>Elevated LDL-cholesterol </li></ul><ul><li>Family history of obesity, CVD, certain cancers </li></ul><ul><li>Pattern of fat distribution </li></ul><ul><li>Elevated blood glucose: diabetes, insulin resistance </li></ul>
  33. 34. Perspective on Weight <ul><li>Unrealistic goals </li></ul><ul><li>Listen to body’s cues (for hunger) </li></ul><ul><li>Eat a healthy diet </li></ul><ul><li>Physical activity </li></ul><ul><li>“Size acceptance” </li></ul>
  34. 35. Obesity <ul><li>Excessive amount of body fat </li></ul><ul><ul><li>Women with > 35% body fat </li></ul></ul><ul><ul><li>Men with > 25% body fat </li></ul></ul><ul><li>Increased risk for health problems </li></ul><ul><li>Are usually overweight, but can have healthy BMI and high % fat </li></ul><ul><li>Measurements using calipers </li></ul>
  35. 36. Estimation of Body Fat <ul><li>Underwater weighing Most accurate </li></ul><ul><ul><li>Fat is less dense than lean tissue </li></ul></ul><ul><ul><li>Fat floats </li></ul></ul><ul><li>Problems with </li></ul><ul><ul><li>Children </li></ul></ul><ul><ul><li>Elderly </li></ul></ul><ul><ul><li>Very large </li></ul></ul><ul><ul><li>Fear of water </li></ul></ul>
  36. 37. Estimation of Body Fat <ul><li>Bioelectrical impedance </li></ul><ul><ul><li>Low-energy current to the body that measures the resistance of electrical flow </li></ul></ul><ul><ul><li>Fat is resistant to electrical flow; the more the resistance, the more body fat you have </li></ul></ul><ul><li>DEXA (dual x-ray photon absorptiometry) </li></ul><ul><ul><li>An X-ray body scan that allows for the determination of body fat </li></ul></ul><ul><li>Infrared light </li></ul><ul><ul><li>Assess the interaction of fat and protein in the arm muscle </li></ul></ul>
  37. 38. Skinfold Thickness <ul><li>Accurate with </li></ul><ul><li>Training </li></ul><ul><li>Good calipers </li></ul><ul><li>Multiple sites </li></ul><ul><li>Multiple measurements </li></ul>
  38. 39. Health Problems Associated with Excess Body Fat <ul><li>Surgical risk </li></ul><ul><li>Lung (pulmonary) disease </li></ul><ul><li>Sleep apnea </li></ul><ul><li>HTN </li></ul><ul><li>CVD </li></ul><ul><li>Bone and joint disorders (gout, osteoarthritis) </li></ul><ul><li>Gallstones </li></ul><ul><li>Cancers (breast, colon, pancreas, gallbladder) </li></ul><ul><li>Infertility </li></ul><ul><li>Pregnancy- difficult delivery </li></ul><ul><li>Reduced agility </li></ul><ul><li>Early death </li></ul>
  39. 40. Desirable % Body Fat <ul><li>Men: 8-25% </li></ul><ul><li>Women 20-35% </li></ul>
  40. 41. Body Fat Distribution <ul><li>Upper-body (android) obesity--apple shape </li></ul><ul><li>Associated with more heart disease, HTN, Type II Diabetes </li></ul><ul><li>Abdominal fat is released right into the liver </li></ul><ul><li>Encouraged by testosterone and excessive alcohol intake </li></ul><ul><li>Defined as waist measurement of > 40” for men and >35” for women </li></ul>
  41. 42. Body Fat Distribution
  42. 43. Body Fat Distribution <ul><li>Lower-body (gynecoid) obesity--Pear shape </li></ul><ul><li>Encouraged by estrogen and progesterone </li></ul><ul><li>After menopause, upper-body obesity appears </li></ul><ul><li>Less health risk than upper-body obesity </li></ul>
  43. 44. Juvenile-Onset Obesity <ul><li>Develops in infancy or childhood </li></ul><ul><li>Increase in the number of adipose cells </li></ul><ul><li>Adipose cells have long lifespan and need to store fat </li></ul><ul><li>Makes it difficult to lose the fat (weight loss) </li></ul>
  44. 45. Adult-Onset Obesity <ul><li>Develops in adulthood </li></ul><ul><li>Fewer (numbers of) adipose cells </li></ul><ul><li>These adipose cells are larger (store excess amount of fat) </li></ul><ul><li>If weight gain continues, the number of adipose cells can increase </li></ul>
  45. 46. Causes of Obesity <ul><li>Nature vs Nurture </li></ul><ul><li>Identical twins raised apart have similar weights </li></ul><ul><li>Genetics account for ~40%-70% of weight differences </li></ul><ul><li>Genes affect metabolic rate, fuel use, brain chemistry, body shape </li></ul><ul><li>Thrifty metabolism gene allows for more fat storage to protect against famine </li></ul>
  46. 47. Nature vs Nurture <ul><li>Obesity tends to run in families </li></ul><ul><li>If both parents are normal weight – 10% chance of obesity in offspring </li></ul><ul><li>If one parent is obese – 40% chance </li></ul><ul><li>If both parents obese – 80% chance </li></ul><ul><li>Is it genetics or learned eating behavior? </li></ul>
  47. 48. Causes of Obesity <ul><li>Nurture debate </li></ul><ul><li>Environmental factors influence weight </li></ul><ul><li>Learned eating habits </li></ul><ul><li>Activity factor (or lack of) </li></ul><ul><li>Poverty and obesity </li></ul><ul><li>Female obesity is rooted in childhood obesity </li></ul><ul><li>Male obesity appears after age 30 </li></ul>
  48. 49. Nature and Nurture <ul><li>Obesity is nurture allowing nature to express itself </li></ul><ul><li>Location of fat is influenced by genetics </li></ul><ul><li>A child of obese parents must always be concerned about his weight </li></ul>
  49. 50. Nature and Nurture <ul><li>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 </li></ul>
  50. 51. Nurture Theory <ul><li>Eating habits </li></ul><ul><li>Overeating learned early in childhood </li></ul><ul><li>Bottle vs breast </li></ul><ul><li>Urging children to eat more, clean their plates </li></ul><ul><li>Use of food as a reward </li></ul>
  51. 52. Food = Love Shelly Thorene Photography
  52. 53. Eating Response to Non-Hunger Cues <ul><li>Boredom/depression/stress </li></ul><ul><li>Food availability </li></ul><ul><ul><li>Increases overeating </li></ul></ul><ul><ul><li>Monotonous diet – eat less </li></ul></ul><ul><li>Media triggers </li></ul><ul><ul><li>Constant advertisements </li></ul></ul><ul><ul><li>Attractive foot </li></ul></ul>
  53. 54. Activity Habits <ul><li>U.S. Physical activity declining </li></ul><ul><ul><li>Work </li></ul></ul><ul><ul><li>Leisure </li></ul></ul><ul><li>U.S. obesity rising </li></ul>
  54. 55. 2005 U.S. Dietary Guidelines: Activity <ul><li>To reduce the risk of chronic disease in adulthood: engage in at least 30 minutes of moderate-intensity physical activity…on most days of the week </li></ul><ul><li>To help manage body weight, engage in…60 minutes of moderate to vigorous intensity activity on most days of the week </li></ul><ul><li>To sustain weight loss in adulthood: participate in at least 60-90 minutes of daily moderate-intensity physical activity while not exceeding calorie requirements </li></ul>
  55. 57. 2005 U.S. Dietary Guidelines: Activity However Exercise Alone is Generally Ineffective in Taking Weight Off!!
  56. 58. Nature Vs. Nurture <ul><li>Those at risk for obesity will face a lifelong struggle with weight </li></ul><ul><li>Gene does not control destiny </li></ul><ul><li>Increased physical activity, moderate intake can promote healthy weight </li></ul>
  57. 59. Set Point Theory <ul><li>Weight is closely regulated by the body </li></ul><ul><li>Genetically predetermined body weight </li></ul><ul><li>Body resists weight change </li></ul><ul><li>Leptin assists in weight regulation </li></ul><ul><li>Weight returns after weight loss </li></ul><ul><li>Reduction in energy intake results in lower metabolic rate </li></ul><ul><li>Ability to shift the set point weight </li></ul>