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Steven N. Blair Departments of Exercise Science & Epidemiology/Biostatistics University of South Carolina

The Role of Physical Activity in the Prevention and Treatment of Obesity Origins of Obesity—2011 Symposium Iowa State University May 9, 2011. Steven N. Blair Departments of Exercise Science & Epidemiology/Biostatistics University of South Carolina. Disclosures.

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Steven N. Blair Departments of Exercise Science & Epidemiology/Biostatistics University of South Carolina

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  1. The Role of Physical Activity in the Prevention and Treatment of ObesityOrigins of Obesity—2011 SymposiumIowa State UniversityMay 9, 2011 Steven N. Blair Departments of Exercise Science & Epidemiology/Biostatistics University of South Carolina

  2. Disclosures • Medical/Scientific Advisory Boards • Jenny Craig, Inc • Alere • Technogym • Cancer Foundation for Life • Santech • Clarity Project • Research Funding • NIH • Body Media • Coca Cola • Department of Defense

  3. Acknowledgements • Co-investigators • Xuemei Sui • Tim Church • James Hebert • Greg Hand • Ian Janssen • Francisco Ortega • Jonatan Ruiz • Steve Hooker • Michael Beets • Sara Wilcox • Chris Riddoch • Andrew Jackson • Paul McAuley • Susumu Sawada • Andy Ness • Post-doctoral scholars • D.C. Lee • Meghan Baruth • Jongkyu Kim • Enrique Artero • PhD students • Amanda Paluch • John Sieverdes • Vaughn Barry • Jonathan Mitchell • Won Byun • Tatiana Warren • Andrea Maslow • Will Lyerly • Ed Archer

  4. Do We Have an Epidemic of Obesity?

  5. Global Trends in Adult Obesity International Obesity Taskforce. http://www.iotf.org/database/index.asp.

  6. Do we know how to prevent obesity? Yes!!!!! Sit less and stand more

  7. How to Stand Detailed instructions from the Department of Health and Human Services

  8. Introducing “Exertol”Your Physical Activity Prescription

  9. Which causes more deaths in the U.S.—smoking or obesity? • ~40% of U.S. adults think obesity causes at least as many deaths as does smoking • ~20% of U.S. adults think obesity causes more deaths than smoking • The truth • Smoking causes ~440,000 deaths/year • Obesity causes ~110,000 deaths/year

  10. Definitions for adultsBody mass index (BMI) – weight/height 2 • Underweight: BMI < 18.5 • Normal weight: BMI 18.5-<25 • Overweight*: BMI 25-<30 • Obesity: BMI 30 + * WHO defines overweight as BMI 25+ Courtesy of Katherine Flegal

  11. SOURCE: Harris 2008 Int J Obesity Courtesy of Katherine Flegal

  12. SOURCE: Harris 2008 Int J Obesity Courtesy of Katherine Flegal

  13. SOURCE: Harris 2008 Int J Obesity Courtesy of Katherine Flegal

  14. SOURCE: Harris 2008 Int J Obesity Courtesy of Katherine Flegal

  15. Courtesy of Katherine Flegal

  16. Obesity and Diabetes • We hear a great deal, in both the scientific literature and popular press, about the epidemics of obesity and diabetes • In fact, some dummies even use the term “diabesity” • What is the rate of type 2 diabetes in U.S. individuals under 45 years of age?

  17. U.S. Rates of Diagnosed Type 2 Diabetes in Persons under 45 Years of Age in 2010 • 1.4% • Of course this is higher than it was in 1980 • 0.6% • Diagnosed diabetes in those under 20 years of age in the U.S. • 0.26% Source: CDC website--

  18. Body Mass Index and Mortality

  19. Relation between mortality and BMI Data from Lew EA: Mortality and weight: insured lives and the American Cancer Society studies. Ann Intern Med103:1024-1029, 1985.

  20. Excess deaths associated with underweight, overweight and obesity[Reference Range 18.5 – 24.9] 82,066 29,843 33,746 BMI 30+: 111,909 deaths -86,094 Flegal et al JAMA 293:1861, 2005

  21. It’s calories that count Energy Out Energy In Portion size High-fat foods Energy dense Low-fiber Soft drinks Snack foods BMR Thermic effect of food Media (TV,PC) Cars No heavy labour Exercise

  22. Cause(s) of the Obesity Epidemic • Increases in energy intake • Decreases in energy expenditure • Changes in specific micro or macronutrients • Combination of increases in intake and decreases in expenditure • 50/50? • 30/70? • 70/30?

  23. Trends in Energy IntakeNHANES 1971-2000 • Data sources • NHANES I—1971-1974 • NHANES II—1976-1980 • NHANES III—1988-1994 • NHANES—1999-2000 • Surveys were representative samples of noninstitutionalized U.S. women and men aged 20 to 74 years Source: MMWR Feb 6, 2004

  24. Trends in Energy Intake1971 to 2000, Men, NHANES Kcal/day Source: MMWR Feb 6, 2004

  25. Trends in Energy Intake1971 to 2000, Women, NHANES Kcal/day Source: MMWR Feb 6, 2004

  26. NHANES Survey Methods 1971-2000 • NHANES I and NHANES II • 24-hour dietary recall, Monday-Friday • NHANES III and NHANES • 24-hour dietary recall, Monday-Sunday • Other changes in methodology included better probing techniques and better training of interviewers • Other changes in dietary behavior included more meals eaten away from home and increasing portion sizes

  27. Jobs in U.S. Over Last 50 Years Church TS et al. PLoS One 2011

  28. Physical Activity Intensity Church TS et al. PLoS One 2011

  29. Daily Occupational Caloric Expenditure -140 daily kcals -120 daily kcals Church TS et al. PLoS One 2011

  30. Men: Predicted vs. NHANES Church TS et al. PLoS One 2011

  31. Women: Predicted vs. NHANES Church TS et al. PLoS One 2011

  32. The Energy Balance Study

  33. Timeline • Your participation in the study will last approximately 13 months. • All enrolled participants will be asked to complete all scheduled measures. Today Activity assessment Baseline Visits 1-3 Month 3 Month 6 Day 7 Day 14 Month 12 Month 9 3 Baseline Visits -2-3 weeks- 6 Follow-up Visits -12 months- -2 weeks-

  34. Food Portion-size Training • Purpose: to help estimate food portion sizes • Helpful for dietary recalls. • Time: 10 minutes.

  35. Dietary Recalls • Dietician will call and ask what you ate the previous day. • Time: 15-20 minutes • Three random recalls will occur after your Baseline Visit 3.

  36. Physical Activity Monitors • You will be wearing 2 monitors • Armband • Lightweight monitor worn on the upper left arm • Estimates energy expenditure and physical activity • ActivPAL • Small device worn on your thigh (under clothing) • Measures sitting and lying down time. • Both monitors should be worn at all times except in water • Wear for 10 days

  37. Body Composition Scan • ~20-25 minutes • It measures: • Fat mass • Lean mass • Requires small radiation exposure. • Less than 1 day's exposure to the sun. • (~ 3 hours of lawn mowing)

  38. Resting Metabolic Rate • Measures the number of calories you burn at rest. • Participant rests: • 45-60 minutes • Quiet room

  39. Cardiorespiratory Fitness, BMI, and Mortality, ACLS Men • 25,389 men followed 8.5 years • 673 deaths in 212,364 MY • Cardiorespiratory fitness assessed by a maximal exercise test • Calculated age-adjusted death rates for BMI and fitness categories Barlow et al. Int J Obes 1995; 19:Suppl 4, S41-4

  40. Assessment of Body Weight • I do not like to subject study participants to the embarrassment of actually measuring their weight, since so many are overweight/obese • We have an undergraduate student estimate height and weight of the participants • We did a validation study by actually measuring height and weight of 100 consecutive participants • The student’s estimate was valid, r=0.4

  41. Age-Adjusted Death Rates by Fitness and BMI Categories Deaths/10,000 MY # deaths 133 189119 63 6717 7519 Man-Yrs 25,53764,10357,00415,00020,7497,34114,3018,240 Results held after adjustment for health status, smoking, glucose, cholesterol, & BP Barlow et al. Int J Obes 1995; 19:Suppl 4, S41-4

  42. Assessment of Body Weight • I do not like to subject study participants to the embarrassment of actually measuring their weight, since so many are overweight/obese • We have an undergraduate student estimate height and weight of the participants • We did a validation study by actually measuring height and weight of 100 consecutive participants • The student’s estimate was valid, r=0.4

  43. RR for All-cause and CVD Mortality in Fit and Unfit ACLS Men by Body Fat Categories Body Fat% Body Fat% All-cause Mortality CVD Mortality *adjusted for age, exam year, smoking, alcohol, & parental history Lee CD, Blair SN, & Jackson AS. Am J Clin Nurt 1999; 69:373-80

  44. Adjusted RR for All-Cause Mortality by Fitness and Waist Circumference • Waist circumference measurements in a subgroup 14,043 men • 162 deaths in 78,008 man-years • RR adjusted for age, examination year, smoking habit, alcohol intake, and parental history of CHD <87 87-<99 99 Lee CD, Blair SN, & Jackson AS. Am J Clin Nurt 1999; 69:373-80

  45. Adjusted RR for All-Cause Mortality by Fitness and BMI, ACLS Women *adj for age, exam year, smoking, & health status Farrell et al. Obes Res. 2002; 10:417-423

  46. Joint Associations of CRF and % Body Fat with All-cause Mortality, ACLS Adults 60+ Death rate/1,000 person-years Deaths 151190 29 72 Rates adjusted for age, sex and exam year Sui M et al. JAMA 2007; 298:2507-16

  47. CVD Mortality Risk* by Fitness and BMI Categories, 2316 Men with Diabetes, 179 CVD Deaths p for trend <0.0001 p for trend <0.0001 p for trend <0.002 Church TS et al. Arch Int Med 2005; 165:2114 *Adj for age and examination year

  48. Attributable Fractions of Health Outcomes For Low Cardiorespiratory Fitness and Other Predictors, ACLS • Attributable fraction (%) is the estimated number of deaths due to a specific characteristic • Based on strength of association • Prevalence of the condition

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