Ch7 Energy Balance and Weight Control


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Ch7 Energy Balance and Weight Control

  1. 1. Chapter 7 Energy Balance and Weight Control Lecture and Animation PowerPoint Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. To run the animations you must be in Slideshow View . Use the buttons on the animation to play, pause, and turn audio/text on or off. Please Note : Once you have used any of the animation controls , you must click in the white background before advancing to the next slide.
  2. 2. Energy Balance <ul><li>65% of adults are overweight </li></ul><ul><li>30% of total population is obese </li></ul><ul><li>Red flags: </li></ul><ul><ul><li>10 pounds of weight gain </li></ul></ul><ul><ul><li>2-inch increase in waist circumference </li></ul></ul>
  3. 4. Energy Balance
  4. 5. Estimating kcal Content in Food
  5. 6. Bomb Calorimeter
  6. 7. Energy In vs. Energy Out
  7. 8. Basal Metabolism <ul><li>Minimum energy expended to keep a resting, awake body alive </li></ul><ul><li>~60-70% of total energy needs </li></ul><ul><li>Includes energy needed for maintaining heartbeat, respiration, body temperature </li></ul><ul><li>Amount of energy needed for basal metabolism varies between individuals </li></ul><ul><li>Approximately 1 kcal/minute </li></ul>
  8. 9. Factors that Influence Basal Metabolism <ul><li>Body surface area (weight, height) </li></ul><ul><li>Lean body mass </li></ul><ul><li>Gender </li></ul><ul><li>Body temperature </li></ul><ul><li>Thyroid hormone </li></ul><ul><li>Nervous system activity </li></ul><ul><li>Age </li></ul><ul><li>Calorie intake </li></ul><ul><li>Pregnancy </li></ul><ul><li>Use of caffeine and tobacco </li></ul>
  9. 10. Physical Activity <ul><li>Increases energy expenditure </li></ul><ul><li>More activity, more energy burned </li></ul><ul><li>Lack of activity is a major cause of obesity </li></ul>
  10. 11. Energy for Activity
  11. 12. 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 calories consumed </li></ul><ul><li>TEF is highest for protein > carbohydrate > fat </li></ul>
  12. 13. Adaptive Thermogenesis <ul><li>Nonvoluntary physical activity </li></ul><ul><ul><li>Triggered by overeating </li></ul></ul><ul><ul><li>Fidgeting and shivering </li></ul></ul><ul><ul><li>Maintenance of muscle tone </li></ul></ul><ul><ul><li>Maintenance of posture </li></ul></ul><ul><li>Overeating </li></ul><ul><ul><li>Increases sympathetic nervous system activity </li></ul></ul><ul><li>Resists weight gain </li></ul><ul><li>Brown Adipose Tissue </li></ul><ul><ul><li>Participates in thermogenesis </li></ul></ul>
  13. 14. Determination of Energy Needs <ul><li>Direct calorimetry </li></ul><ul><ul><li>Measures heat output </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 consumed </li></ul></ul><ul><ul><li>Oxygen consumed is related to energy expended </li></ul></ul>
  14. 15. Estimated Energy Requirement (EER) <ul><li>Men 19 years and older: </li></ul><ul><li>EER= 662-(9.53 x AGE) + PA x (15.91 x WT + 539.6 x HT) </li></ul><ul><li>Women 19 years and older: </li></ul><ul><li>EER= 354- (6.91 x AGE) + PA x (9.36 x WT + 726 x HT) </li></ul><ul><ul><li>PA = physical activity estimate </li></ul></ul><ul><ul><li>WT = weight in kg </li></ul></ul><ul><ul><li>HT = height in meters (inches / 39.4) </li></ul></ul>
  15. 16. Physical Activity Estimate ACTIVITY LEVEL PA (MEN) PA (WOMEN) Sedentary (no exercise) 1.00 1.00 Low Activity (walks the equivalent of ~2 miles/day) 1.11 1.12 Active (walks the equivalent of ~7 miles/day) 1.25 1.27 Very Active (walks the equivalent of ~17 miles/day) 1.48 1.45
  16. 17. What is a Healthy Body Weight? <ul><li>Current height/weight standards </li></ul><ul><ul><li>Weight associated with health and longevity </li></ul></ul><ul><ul><li>May not be the healthiest weight for individual </li></ul></ul><ul><li>Review of family history </li></ul><ul><li>Personal weight history </li></ul><ul><li>Healthy lifestyle contribution </li></ul>
  17. 18. Weight-Related Conditions
  18. 19. A Healthy Body Weight <ul><li>What is the lowest weight maintained for more than a year? </li></ul><ul><li>What weight was maintained without constantly feeling hungry? </li></ul><ul><li>Establish a “personal” healthy weight </li></ul>
  19. 20. BMI: Overweight and Obesity <ul><li>Underweight = BMI < 18.5 </li></ul><ul><li>Healthy weight = BMI 18.5-24.9 </li></ul><ul><li>Overweight = BMI 25-29.9 </li></ul><ul><li>Obese = BMI 30-39.9 </li></ul><ul><li>Severely obese = BMI >40 </li></ul>
  20. 21. Body Mass Index
  21. 22. Height / Weight Table
  22. 23. Perspective on Weight <ul><li>Aim for personal healthy weight </li></ul><ul><li>Avoid 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>Be physically active </li></ul><ul><li>“ Size acceptance” </li></ul>
  23. 24. Obesity <ul><li>Excessive amount of body fat </li></ul><ul><ul><li>Women > 35% body fat </li></ul></ul><ul><ul><li>Men > 24% body fat </li></ul></ul><ul><li>Increased risk for health problems </li></ul><ul><li>Are usually truly overweight </li></ul>
  24. 25. Estimation of Body Fat <ul><li>Underwater weighing </li></ul><ul><li>Very accurate </li></ul><ul><li>Fat is less dense than lean tissue </li></ul><ul><li>Fat floats </li></ul>
  25. 26. Underwater Weighing
  26. 27. Estimation of Body Fat <ul><li>Air displacement </li></ul><ul><li>Determines the body volume </li></ul><ul><ul><li>Displace air in a sealed chamber </li></ul></ul><ul><li>Body density = </li></ul><ul><li>Body wt/body volume </li></ul><ul><li>% Body fat= </li></ul><ul><li>(495/body density)-450 </li></ul>
  27. 28. Bod Pod
  28. 29. Skinfold Measurements
  29. 31. Estimation of Body Fat <ul><li>Bioelectrical impedance </li></ul><ul><ul><li>Low-energy current 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 </li></ul></ul><ul><li>DEXA (dual x-ray photon absorptiometry) </li></ul><ul><ul><li>X-ray body scan that allows for the determination of body fat </li></ul></ul><ul><ul><li>Most accurate but expensive </li></ul></ul>
  30. 32. Dual X-ray Photon Absorptiometry
  31. 33. Body Fat Distribution <ul><li>Upper-body obesity, “Apple shape” </li></ul><ul><li>Associated with </li></ul><ul><ul><li>Cardiovascular disease, HTN, type 2 diabetes </li></ul></ul><ul><ul><li>Testosterone and excessive alcohol </li></ul></ul><ul><ul><li>Abdominal fat is released into the liver and promotes inflammation in the body </li></ul></ul><ul><li>Defined as </li></ul><ul><ul><li>Waist measurement of > 40 ” for men </li></ul></ul><ul><ul><li>Waist measurement of >35 ” for women </li></ul></ul>
  32. 34. Body Fat Distribution
  33. 35. Body Fat Distribution <ul><li>Lower-body obesity, “Pear shape” </li></ul><ul><li>Encouraged by estrogen and progesterone </li></ul><ul><li>After menopause, upper-body obesity more common </li></ul><ul><li>Fewer health risks than upper-body obesity </li></ul>
  34. 36. 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 fat (weight loss) </li></ul>
  35. 37. War on obesity
  36. 38. Adult-Onset Obesity <ul><li>Develops in adulthood </li></ul><ul><li>Fewer (number of) adipose cells </li></ul><ul><li>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>
  37. 39. Obesity and Nature Debate <ul><li>Identical twins </li></ul><ul><ul><li>When raised apart still have similar weights </li></ul></ul><ul><li>Genes </li></ul><ul><ul><li>Affect metabolic rate, fuel use, brain chemistry, body shape </li></ul></ul><ul><ul><li>Account for up to 70% of weight differences </li></ul></ul><ul><li>Thrifty metabolism gene </li></ul><ul><ul><li>More fat storage to protect against famine </li></ul></ul>
  38. 40. Set-Point Theory <ul><li>Weight is 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>Reduction in calorie intake results in lower metabolic rate </li></ul><ul><li>Ability to shift the set-point weight? </li></ul>
  39. 41. Opponents of Set-Point Theory <ul><li>Weight does not remain constant </li></ul><ul><li>Different environments can alter weight </li></ul><ul><li>People settle into a particular weight based on current circumstances </li></ul>
  40. 42. Obesity and Nurture Debate <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>
  41. 43. 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>Child of obese parents is especially at risk </li></ul><ul><li>Increased physical activity and moderate calorie intake can promote healthy weight </li></ul>
  42. 44. What Encourages Excess Body Fat?
  43. 45. Why Diets Don ’t Work <ul><li>Obesity is a chronic disease </li></ul><ul><ul><li>Treatment requires long-term lifestyle changes </li></ul></ul><ul><li>Dieters are misdirected </li></ul><ul><ul><li>More concerned about weight loss than healthy lifestyle </li></ul></ul><ul><ul><li>Unrealistic weight expectations </li></ul></ul>
  44. 46. Looking for a Sound Weight-Loss Program? <ul><li>Seek advice from a Registered Dietitian </li></ul><ul><li>Control calorie intake </li></ul><ul><li>Increase physical activity </li></ul><ul><li>Acknowledge need for lifelong changes to maintain healthy weight </li></ul>
  45. 47. Weight-Loss Triad
  46. 48. Control Calories <ul><li>Sedentary society---requires less calories </li></ul><ul><li>Low-fat, high-fiber approaches </li></ul><ul><ul><li>Most successful in long-term studies </li></ul></ul><ul><li>No diet has a “metabolic advantage” </li></ul><ul><li>Read food labels </li></ul><ul><li>Keep a food log (portion size awareness) </li></ul>
  47. 49. Regular Physical Activity <ul><li>Important for weight maintenance </li></ul><ul><li>Promotes steady weight loss </li></ul><ul><ul><li>Expends 100-300 kcal while controlling calories </li></ul></ul><ul><li>Boosts self-esteem </li></ul><ul><li>Add weight resistance </li></ul><ul><ul><li>Increase lean body mass </li></ul></ul><ul><ul><li>Increase fat use </li></ul></ul><ul><ul><li>Increase bone health </li></ul></ul><ul><ul><li>Increase metabolic rate </li></ul></ul>
  48. 50. Physical Activity Recommendations <ul><li>60 minutes/day to maintain body weight </li></ul><ul><li>60-90 minutes/day for maintenance of weight loss </li></ul><ul><li>Pedometer </li></ul><ul><ul><li>Goal 10,000 steps a day </li></ul></ul>
  49. 51. What it Takes to Lose a Pound <ul><li>Body fat contains 3500 kcal per pound </li></ul><ul><li>Fat storage (body fat plus supporting lean tissues) contains 3300 kcal per pound </li></ul><ul><li>Must have an energy deficit of about 3300 kcal to lose a pound per week </li></ul>
  50. 52. Do the Math To lose one pound, you must create a deficit of 3300 kcal So to lose a pound in 1 week (7 days), try cutting back on your kcal intake and increase physical activity so that you create a deficit of about 500 kcal per day - 500 kcal x 7 days = - 3500 kcal = ~ 1 pound of weight day week loss in 1 week
  51. 53. Sound Weight Loss Program <ul><li>Rate of loss </li></ul><ul><li>Flexibility </li></ul><ul><li>Intake </li></ul><ul><li>Behavior modification </li></ul><ul><li>Overall health </li></ul>
  52. 54. Behavior Modification <ul><li>Modify problem (eating) behaviors </li></ul><ul><li>Chain-breaking </li></ul><ul><li>Stimulus control </li></ul><ul><li>Cognitive restructuring </li></ul><ul><li>Contingency management </li></ul><ul><li>Self-monitoring </li></ul>
  53. 55. Chain-Breaking <ul><li>Breaking the link between two behaviors </li></ul><ul><li>These links can lead to excessive intake </li></ul>
  54. 56. Stimulus Control <ul><li>Altering the environment </li></ul><ul><ul><li>Minimize the stimuli for eating </li></ul></ul><ul><li>Putting you in charge of temptations </li></ul>
  55. 57. Cognitive Restructuring <ul><li>Changing your frame of mind regarding eating </li></ul><ul><li>Replacing eating due to stress with “walking” </li></ul>
  56. 58. Contingency Management <ul><li>Forming a plan of action </li></ul><ul><ul><li>Response to a situation </li></ul></ul><ul><li>Rehearsing appropriate responses </li></ul><ul><ul><li>The pressure of eating at parties </li></ul></ul>
  57. 59. Self-Monitoring <ul><li>Tracking foods eaten and conditions affecting eating </li></ul><ul><li>Understanding your eating habits </li></ul>
  58. 60. Weight Maintenance <ul><li>Prevent relapse </li></ul><ul><ul><li>Occasional lapse is fine, but take charge immediately </li></ul></ul><ul><ul><li>Continue to practice newly learned behavior </li></ul></ul><ul><ul><li>Requires “motivation, movement, and monitoring” </li></ul></ul><ul><li>Have social support </li></ul><ul><ul><li>Encouragement from friends/ family/ professionals </li></ul></ul>
  59. 61. Diet Drugs <ul><li>Amphetamine (Phenteramine) </li></ul><ul><ul><li>Prolongs the activity of epinephrine and norepinephrine in the brain </li></ul></ul><ul><ul><li>Decreases appetite </li></ul></ul><ul><ul><li>Not recommended for long-term use (dependency) </li></ul></ul><ul><li>Sibutramine (Meridia) </li></ul><ul><ul><li>Enhances norepinephrine and serotonin activity </li></ul></ul><ul><ul><li>Decreases appetite </li></ul></ul><ul><ul><li>Not recommended for people with HTN </li></ul></ul>
  60. 62. Orlistat (Xenical) <ul><li>Inhibits (lipase) fat digestion </li></ul><ul><li>Reduces absorption of fat by 30% in the small intestine </li></ul><ul><li>Dietary fat is deposited in the feces, with resulting side effects </li></ul><ul><li>Must still control fat intake </li></ul><ul><li>Malabsorption of fat-soluble vitamins </li></ul><ul><li>Supplement needed at bedtime </li></ul><ul><li>Alli---Low dose of Orlistat, available OTC </li></ul>
  61. 63. Orlistat (Xenical)
  62. 64. Treatment of Severe Obesity
  63. 65. Very Low-Calorie Diets (VLCD) <ul><li>Recommended for people >30% above their healthy weight </li></ul><ul><li>400-800 kcal per day </li></ul><ul><li>Low carbohydrate and high protein </li></ul><ul><li>Cause ketosis </li></ul><ul><li>Lose ~3-4 pounds a week </li></ul><ul><li>Require careful physician monitoring </li></ul><ul><li>Health risks include cardiac problems and gallstones </li></ul>
  64. 66. Bariatric Surgery
  65. 67. Adjustable Gastric Banding <ul><li>Reduces opening from esophagus to stomach by gastric band </li></ul><ul><li>Decreases amount of food eaten </li></ul><ul><li>Band can be inflated or deflated </li></ul>
  66. 68. Gastroplasty - Stomach Stapling <ul><li>Most common surgical procedure for treating severe obesity </li></ul><ul><li>Reduces the stomach size </li></ul><ul><ul><li>From 4 cups to 1 oz (shot glass size) </li></ul></ul><ul><li>Overeating will result in rapid vomiting </li></ul><ul><li>Smaller stomach promotes satiety earlier </li></ul><ul><li>75% will lose ~50% of excess body weight </li></ul>
  67. 69. Gastroplasty
  68. 70. Criteria for Gastroplasty <ul><li>BMI > 40 </li></ul><ul><li>Obese for > 5 years </li></ul><ul><li>No history of alcoholism </li></ul><ul><li>No history of major psychiatric disorder </li></ul><ul><li>Costly procedure </li></ul><ul><li>Follow-up needed after procedure loss </li></ul><ul><li>Requires major lifestyle changes </li></ul>
  69. 71. Underweight is Also a Problem <ul><li>BMI of <18.5 </li></ul><ul><li>Associated with increased deaths, menstrual dysfunction, pregnancy complications, slower recovery from illness/surgery </li></ul>
  70. 72. Treatment for Underweight <ul><li>Intake of energy-dense foods (energy input) </li></ul><ul><li>Encourage regular meals and snacks </li></ul><ul><li>Reduce activity (energy output) </li></ul><ul><li>Increase portion size </li></ul><ul><li>Strength training </li></ul>
  71. 73. Fad Diets <ul><li>Promote quick weight loss </li></ul><ul><li>Limited food selections </li></ul><ul><li>Use of testimonials </li></ul><ul><li>Cure-alls </li></ul><ul><li>Recommend expensive supplements </li></ul><ul><li>No permanent lifestyle changes advocated </li></ul><ul><li>Critical of the scientific community </li></ul>
  72. 74. Types of Popular Diets <ul><li>Low or restricted carbohydrates </li></ul><ul><li>Carbohydrate focused diets </li></ul><ul><li>Low-fat approaches </li></ul><ul><li>Novelty diets </li></ul><ul><li>Meal replacements </li></ul>
  73. 75. Low-carb diets take off pounds but at what risk?
  74. 76. Popular Diets