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  1. 1. Obesity & Body Composition
  2. 2. Physical Activity
  3. 3. Physical Activity <ul><li>Larger individuals burn more calories for the same activity </li></ul><ul><li>100 kcals/mile walking, running or swimming </li></ul><ul><li>50-80 kcals/mile for cycling </li></ul>
  4. 4. Physical Activity
  5. 7. Physical Activity <ul><li>CDC </li></ul><ul><li>Moderate-intensity physical activity generally requires sustained rhythmic movements and refers to a level of effort equivalent to </li></ul><ul><ul><li>A &quot;perceived exertion&quot; of 11 to 14 on the Borg scale </li></ul></ul><ul><ul><li>3 to 6 metabolic equivalents ( METs ) ; </li></ul></ul><ul><ul><li>Any activity that burns 3.5 to 7 Calories per minute (kcal/min); or </li></ul></ul><ul><li>The effort a healthy individual might expend while walking briskly, mowing the lawn, dancing, swimming, or bicycling on level terrain, for example. </li></ul><ul><li>A person should feel some exertion but should be able to carry on a conversation comfortably during the activity. </li></ul>
  6. 8. Physical Activity <ul><li>Exercise alone can lead to weight loss </li></ul><ul><li>However, it is insufficient for long-term weight loss </li></ul><ul><li>Exercise and caloric restriction is more effective </li></ul><ul><li>Exercise does help offset lean muscle mass loss from low calorie diets </li></ul><ul><li>Unknown how physical activity affects food intake </li></ul>
  7. 9. Physical Activity -Endurance Training <ul><li>A single session of exercise may only burn 300 calories </li></ul><ul><li>However, 3-4 times a week over a year will result in a loss of 13-23 pounds </li></ul><ul><li>As fitness level improves, exercise may be more effective </li></ul><ul><ul><li>Improved fat metabolism during exercise </li></ul></ul><ul><ul><li>Increase resting metabolic rate </li></ul></ul>
  8. 10. Physical Activity – Weight Training <ul><li>Fewer calories are burned per minute compared to endurance exercise </li></ul><ul><li>Greater increase in muscle mass and resting metabolic rate </li></ul><ul><li>Isn’t as effective as endurance exercise even when combined with dieting </li></ul><ul><li>Can’t spot reduce </li></ul>
  9. 11. Physical Activity - Spot Reduction <ul><li>Can’t happen. </li></ul><ul><li>Fat cell and muscle cells are not directly connected. </li></ul><ul><li>Hormones that mobilize lipids don’t work on individual cells. </li></ul><ul><li>Lower body fat is more “resistant” fat compared to upper body fat. </li></ul>
  10. 12. Physical Activity - Misconceptions <ul><li>1. Exercise increases food intake </li></ul><ul><li>2. Few calories are burned during exercise </li></ul>
  11. 13. Physical Activity <ul><li>Higher metabolic rate </li></ul><ul><li>Better insulin control </li></ul><ul><li>Dose-response relationship </li></ul><ul><li>Guidelines </li></ul><ul><ul><li>Start slowly </li></ul></ul><ul><ul><li>Consistency </li></ul></ul><ul><ul><li>Duration over intensity </li></ul></ul><ul><ul><li>Resistance training </li></ul></ul>
  12. 14. Physical Activity - Exercise <ul><li>1500 kcals/week as a minimum </li></ul><ul><li>Most effective with 200-300 minutes of physical activity per week </li></ul><ul><li>Exercise intensity for increasing RMR </li></ul><ul><li>Can’t spot reduce </li></ul><ul><li>Post-exercise caloric cost will add 15-50% </li></ul><ul><li>Exercise plus diet is more effective than diet for maintaining weight loss </li></ul><ul><li>Diet alone can decrease RMR up to 30% </li></ul>
  13. 17. Successful weight loss maintenance. Author: Wing, Rena R.; Hill, James O. Source: Annual Review of Nutrition v. 21 (2001) p. 323-41 SUMMARY   Successful weight loss = intentional weight loss of greater than or equal to 10% of initial body weight that is maintained at least 1 year be considered success. According to this definition, approximately 20% or more of individuals who attempt weight loss would be &quot;successful.&quot; Although the National Weight Control Registry (NWCR) does not provide information about how many people achieve long-term weight loss success, it does provide information about strategies used to achieve and maintain a weight loss. With regard to weight loss, the most obvious conclusion from the NWCR is that weight loss should include both changing diet and increasing physical activity . We do not, however, see any particular type of diet modification to achieve the weight loss that is common to these successful weight loss maintainers.
  14. 18. We believe that strategies for weight loss maintenance may be the key to long-term weight management success. We find three behaviors in a vast majority of NWCR subjects. First, these subjects engage in high levels of physical activity ( 1 hour per day ) Second, these subjects report eating a diet low in fat and high in carbohydrate . Third, these subjects report regular self-monitoring of weight . Currently, the data seem to suggest that differences in behavior are stronger predictors of weight regain than the differences in physiology or metabolism. Part of the reasons for developing the NWCR was to counter the belief that &quot;no one succeeds long-term at weight loss.&quot; We believe the subjects in the NWCR show that you can achieve and maintain substantial amounts of weight loss. Furthermore, we have found that these subjects live &quot;normal&quot; lives after weight loss and consistently report that life is better after weight loss. Our subjects tell us that their success requires substantial effort but that it is worth it. Finally, our data suggest that over time, it does get easier to maintain weight loss. It may be a lifelong struggle, but once you have maintained a weight loss for 2-5 years, the chances of longer-term success greatly increase.
  15. 19. Physical Activity and Diet <ul><li>Goal. Lose 1 pound per week </li></ul><ul><li>Require 500 calorie deficit per day </li></ul><ul><li>Walking or jogging 5 miles a day </li></ul><ul><li>Or, walk/jog 2.5 miles a day and eat 250 less calories per day. </li></ul><ul><li>However, if burn 500 calories a day and eat 250 less a day, lose 1.5 pounds per week. </li></ul>
  16. 20. Physical Activity - Weight Control <ul><li>Obesity is not simple a problem of gluttony </li></ul><ul><li>Caloric intake per person has decreased for the past 100 years </li></ul>
  17. 21. Behavior Modification <ul><li>Self-monitoring – patterns of eating and exercise </li></ul><ul><li>Stimulus control – controlling the environment </li></ul><ul><li>Reinforcement – rewards </li></ul><ul><li>Nutrition - knowledge </li></ul><ul><li>Exercise and physical activity </li></ul><ul><li>Social support </li></ul><ul><li>Cognitive change - attitudes </li></ul>
  18. 22. Eating Disorders
  19. 23. Eating Disorders <ul><li>Anorexia nervosa </li></ul><ul><li>Bulemia nervosa </li></ul><ul><li>Binge eating </li></ul>
  20. 24. Eating Disorders
  21. 25. Anorexia Nervosa <ul><li>Individuals who have anorexia nervosa do not eat enough food to maintain a reasonable body weight, and they have an intense fear of getting fat. They engage in compulsive behaviors to keep from eating and commonly use prolonged exercise to reduce body weight. </li></ul><ul><li>Anorexia affects 1–3 million Americans, 90% of whom are women, and it typically occurs between the ages of 12 and 18. </li></ul><ul><li>Medical complications include disorders of the cardiovascular, gastrointestinal, and endocrine systems; cessation of menstruation; and even death from heart failure. </li></ul>
  22. 26. Bulemia Nervosa <ul><li>This disorder is characterized by binge eating from 1000–60,000 calories and then purging through vomiting and/or the use of laxatives or diuretics. </li></ul><ul><li>The strain on the body is enormous, and the health effects include tooth decay, esophageal damage, chronic hoarseness, menstrual irregularities, depression, liver and kidney damage, and cardiac arrhythmia. </li></ul>
  23. 27. Binge Eating <ul><li>Characterized by uncontrolled eating without purging, binge eating often results in weight gain and feelings of guilt, shame, and depression. </li></ul><ul><li>Individuals with binge-eating disorder do not eat because they are hungry; rather, they eat as a coping mechanism for stress, conflict, and emotional difficulty. </li></ul>
  24. 28. Weight Loss <ul><li>Accurate assessment of body composition (not society) </li></ul><ul><li>Eat less fat and less high glycemic index foods </li></ul><ul><li>Aerobic exercise emphasizing duration </li></ul><ul><li>Resistance exercise with proper rest </li></ul><ul><li>Patience and realistic </li></ul>
  25. 29. Body Composition
  26. 30. Classification of Obesity <ul><li>CDC </li></ul><ul><li>Percent body fat </li></ul><ul><li>Greater than 25% for men </li></ul><ul><li>Greater than 33% for women </li></ul>Dr. Emmett. Spring Break 2003
  27. 31. Criteria for Obesity <ul><li>Men greater than 20% </li></ul><ul><li>Women greater than 30% </li></ul>
  28. 32. Body Mass Index <ul><li>kg/m 2 </li></ul><ul><li>Health risks </li></ul><ul><ul><li>Moderate less than 20 </li></ul></ul><ul><ul><li>Very Low 20-25 </li></ul></ul><ul><ul><li>Low 25-30 </li></ul></ul><ul><ul><li>Moderate 30-35 </li></ul></ul><ul><ul><li>High 35-40 </li></ul></ul>
  29. 34. Body Mass Index and Waist Circumference Men <40 >40 Women <40 >40 -- -- -- -- Increase High High Very High Very High Very High Extremely high Extremely high Disease risk relative to normal weight and waist circumference Note: Research suggests that a low BMI can be healthy in some cases, as long as it is not the result of smoking, eating, disorder, or an underlying disease process.
  30. 35. Waist to Hip Ratio <ul><li>Waist/hip circumference </li></ul><ul><ul><li>Very high risk if greater than 0.82 for women and 0.90 for women over 60 </li></ul></ul><ul><ul><li>Very high risk if greater than 0.94 for men and 1.03 for men over 60 </li></ul></ul><ul><li>Android (apple) </li></ul><ul><li>Gynoid (pear) </li></ul><ul><li>Which is most unhealthy? </li></ul><ul><li>Android </li></ul><ul><li>Why? </li></ul><ul><li>Fat release directly into portal vein and to the liver which stimulates cholesterol production </li></ul>
  31. 36. Regional Fat Distribution <ul><li>Central or Android or Apple </li></ul><ul><li>Peripheral or Gynoid or Pear </li></ul><ul><li>Ratio limits </li></ul><ul><ul><li>0.8 for women </li></ul></ul><ul><ul><li>0.95 for men </li></ul></ul><ul><li>Lipoprotein Lipase </li></ul>
  32. 37. Body Composition <ul><li>Fat mass </li></ul><ul><li>Fat-free mass </li></ul><ul><ul><li>Bone </li></ul></ul><ul><ul><li>Water </li></ul></ul><ul><ul><li>Muscle </li></ul></ul><ul><ul><li>Organs </li></ul></ul>
  33. 38. Desirable Body Mass <ul><li>Brooks,Fahey, White, and Baldwin </li></ul><ul><ul><li>Men less than 20% </li></ul></ul><ul><ul><li>Women 16-25% </li></ul></ul><ul><li>McArdle, Katch and Katch </li></ul><ul><ul><li>Men 15% </li></ul></ul><ul><ul><li>Women 25% </li></ul></ul><ul><li>ACSM 50 th percentile (20-29 up to 60+) </li></ul><ul><ul><li>Men 15.9 to 23.5% </li></ul></ul><ul><ul><li>Women 22.1 to 30.9% </li></ul></ul><ul><li>Fahey, Insel, and Roth (Acceptable) </li></ul><ul><ul><li>Men 12-20% </li></ul></ul><ul><ul><li>Women 20-30% </li></ul></ul><ul><li>Jackson and Pollack (Average for 20-29 year olds) </li></ul><ul><ul><li>Men 14-20% </li></ul></ul><ul><ul><li>Women 20-28% </li></ul></ul>
  34. 39. Measuring Body Composition <ul><li>Dissection </li></ul>
  35. 40. Hydrostatic Weighing <ul><li>Which weighs more, a pound of fat or a pound of muscle? </li></ul><ul><li>Which is more dense, a pound of fat or a pound of muscle? </li></ul><ul><li>Why the difference? </li></ul>
  36. 41. Hydrostatic Weighing <ul><li>Archimedes and King Hieron </li></ul><ul><li>“ Arch” knew that density = mass / volume </li></ul><ul><li>Arch knew the mass of the crown </li></ul><ul><li>Volume = mass on land - mass in water </li></ul><ul><li>Arch underwater weighed gold and silver each with the same mass as the crown </li></ul><ul><li>However, the volume for the gold was different from the crown. </li></ul><ul><li>“ Eureka, the crown is a fraud.” </li></ul>
  37. 42. Hydrostatic Weighing <ul><li>Assumptions </li></ul><ul><ul><li>FFM density is 1.1 g/ml </li></ul></ul><ul><ul><li>Fat mass = 0.902 g/ml </li></ul></ul><ul><li>Theory </li></ul><ul><ul><li>Fat has a different density from Lean Body Mass </li></ul></ul><ul><ul><li>Density = Mass / Volume </li></ul></ul><ul><ul><li>UWW determines volume </li></ul></ul><ul><ul><ul><li>Dry weight minus Under water weight = volume </li></ul></ul></ul><ul><ul><li>With volume and mass can calculate body density (Db) </li></ul></ul><ul><ul><li>Siri or Brozek equation converts Db to %BF </li></ul></ul>
  38. 43. Hydrostatic Weighing <ul><li>Errors </li></ul><ul><ul><li>Equations </li></ul></ul><ul><ul><li>Residual lung volume </li></ul></ul><ul><ul><li>Water density </li></ul></ul><ul><ul><li>Consistency of tissues across races, gender, age </li></ul></ul><ul><li>Recommended Technique. </li></ul><ul><ul><li>Water tank </li></ul></ul><ul><ul><li>Nitrogen wash out </li></ul></ul><ul><ul><li>Weight belt </li></ul></ul><ul><ul><li>Maximal exhalation </li></ul></ul><ul><ul><li>Repeat 8-12 times </li></ul></ul><ul><li>r = 0.94 </li></ul>
  39. 44. Dr. Pritschet Dr. Emmett JE BP
  40. 45. Hydrostatic Weighing <ul><li>Example. A person weighs 75 kg in air and 3 kg in water. </li></ul><ul><li>72 kg of water was displaced </li></ul><ul><li>72 kg of water = 72 liters or 72,000 cm 3 </li></ul><ul><li>Therefore the density would equal 75 kg / 72,000 cm 3 , or 1.0416 g/cm 3 </li></ul><ul><li>So? </li></ul>
  41. 46. Hydrostatic Weighing <ul><li>D = F + L / (F/f) + (L/l) </li></ul><ul><li>Too complicated? </li></ul><ul><li>Body fat = (495 / D) - 450 </li></ul><ul><li>This is the Siri equation. </li></ul><ul><li>Brozek = (457/Db) – 4.142 </li></ul><ul><li>If all measurements are correct, it has a 1% margin of error for body fats between 4 and 30%. </li></ul>
  42. 47. Hydrostatic Weighing <ul><li>Advantages ? </li></ul><ul><ul><li>Good accuracy </li></ul></ul><ul><li>Disadvantages ? </li></ul><ul><ul><li>Water </li></ul></ul><ul><ul><li>Costs </li></ul></ul>
  43. 48. Duel-Energy X-Ray Absorptiometry (DEXA) <ul><li>Developed to measure bone density </li></ul><ul><li>Can measure bone, non-bone, and fat density </li></ul><ul><li>New gold standard? </li></ul><ul><li>Comparison </li></ul><ul><ul><li>Error = ±1-5% </li></ul></ul><ul><ul><ul><li>Software </li></ul></ul></ul><ul><ul><ul><li>Body sections differences </li></ul></ul></ul><ul><ul><li>Very costly </li></ul></ul><ul><ul><li>Very high tech </li></ul></ul><ul><ul><li>Quick, subject friendly </li></ul></ul>
  44. 49. Biochemical Techniques <ul><li>Potassium </li></ul><ul><ul><li>Constant proportion within muscle mass. </li></ul></ul><ul><li>Total Body Water </li></ul><ul><ul><li>Deuterium, heavy water, etc. </li></ul></ul><ul><ul><li>FFM = TBW (L)/0.732 </li></ul></ul><ul><li>Fat Soluble Inert Gas Absorption </li></ul><ul><li>Accurate but expensive </li></ul>
  45. 50. Skin folds <ul><li>Theory. Relationship between fatfolds and total fat mass </li></ul><ul><li>Fat folds used to determine density . </li></ul><ul><li>Density used to estimate percent body fat. </li></ul><ul><li>Assumptions </li></ul>
  46. 51. <ul><li>1. All measurements should be taken from the right side of the body. The skinfold site should be marked with a black felt tip pen. </li></ul><ul><li>2. Pick up the skinfold with you left the index finger and thumb. Be sure you have two layers of skin and the underlying fat. To make sure it is a true skinfold and not muscle, check by having the subject contract the underlying muscle as you are grasping the skin - and then relax before taking a reading. </li></ul><ul><li>3. The calipers should be held in the right hand perpendicular to the fold, with the dial face up and easy to read. The calipers should be place 1/4 to 1/2 inches away from the fingers holding the skinfold , so that the pressure of the calipers will not be affected. </li></ul><ul><li>4. Apply the calipers about 1 cm. below the fingers. It should be applied where the two surfaces of the folds are parallel. Do not apply the calipers where the fold is rounded near the top, or where it is broader near its base. Keep holding the skin as measures are read. </li></ul><ul><li>5. Measure all skinfolds to the nearest 0.5 mm as you continue to grasp the skin. Measure one site once, then the next site once and so on until you have measured all sites once. Then repeat the cycle a minimum of three times at each site. Use the average of the scores at each site for the final skinfold score. If there is a question as to the accuracy of the measure, discard that measure and remeasure. The measurements at each site should be within 5 percent accuracy, i.e., if the first measurement is 20 mm., the second measurement should be 20 + or - 1 (0.5 X 20 = 1). The person who is measuring should not know the results of the first measurement when taking the second and so on. </li></ul><ul><li>6. During the measurement, constant pressure must be maintained by the thumb and forefinger. </li></ul><ul><li>7. Measurements should not be taken under the following conditions: When the skin is moist or wet, after exercise, or when the subject is overheated, because these conditions will cause larger skinfolds and, consequently, larger values. </li></ul>
  47. 52. Skin folds <ul><li>Calipers </li></ul><ul><ul><li>constant tension </li></ul></ul><ul><ul><li>true double layer </li></ul></ul><ul><ul><li>two seconds </li></ul></ul><ul><li>Sites </li></ul><ul><ul><li>right side of the body </li></ul></ul><ul><ul><li>minimum of 2 locations </li></ul></ul><ul><ul><li>exact locations </li></ul></ul>
  48. 53. Skin folds <ul><li>Measurements: sum of fat folds and percent body fat. </li></ul><ul><li>Advantages: cheaper, quicker, comfort, mobile </li></ul><ul><li>Disadvantages: obese, experience, equation, </li></ul><ul><li>3-5% error </li></ul>
  49. 54. Skin Fold Equations <ul><li>Females : </li></ul><ul><li>Db = 1.0994921 - (0.0009929 X sum of 3 SKFs) + (0.0000023 X [sum of 3 SKFs]2) - (0.0001392 X age). </li></ul><ul><li>Males: </li></ul><ul><li>Db = 1.0938 - (0.0008267 X sum of 3 SKFs*) + (0.0000016 X [sum of 3 SKFs]2) - (0.0002574 X age). </li></ul><ul><li>Siri: Percent fat: 4.95 - 4.50 X 100                             Db </li></ul><ul><li>Brozek: Percent fat: 4.570 - 4.142 X 100                                    Db </li></ul>
  50. 55. Bioelectrical Impedance <ul><li>Assumptions </li></ul><ul><ul><li>Fat-free mass = 73.2% water </li></ul></ul><ul><ul><li>UWW is accurate </li></ul></ul>
  51. 56. Bioelectrical Impedance <ul><li>Theory. </li></ul><ul><li>Human body is 67 to 74% water </li></ul><ul><li>Adipose tissue has far less water than other tissues </li></ul><ul><li>FFM low resistance to electrical flow where FM high resistance. </li></ul><ul><li>Technique </li></ul>
  52. 57. Bioelectrical Impedance <ul><li>Advantages: quick, easy, cost?, </li></ul><ul><li>Disadvantages: differences in equipment, body water level, skin temp, equations, </li></ul>
  53. 58. Other Techniques <ul><li>CT scan, MRI, DEXA </li></ul><ul><li>Bod Pod </li></ul><ul><ul><li>under “air” weighing </li></ul></ul><ul><ul><li>air displacement </li></ul></ul><ul><li>Ultrasound - thickness </li></ul><ul><li>X-ray - thickness </li></ul>
  54. 59. Air Plethysmography (Bod Pod)
  55. 60. Air Plethysmography (Bod Pod) <ul><li>Similar principle as UWW only it uses air instead of water </li></ul><ul><li>Comparison </li></ul><ul><ul><li>Error = ±2-3% </li></ul></ul><ul><ul><li>Costly </li></ul></ul><ul><ul><li>Convenient for subject </li></ul></ul><ul><ul><li>Low tech skills </li></ul></ul>