Moderate Exercise Not Enough to Prevent or Reverse Obesity
The American College of Sports Medicine (ACSM) convened a conference, "Physical Activity in the Prevention and Treatment of Obesity and Its Co-Morbidities," on February 46, 1999, in Indianapolis, Ind.
The conference focused on the role of physical activity in obesity and medical conditions associated with it, such as cardiovascular disease, and published the conference proceedings. (See Appendix 1 for a list of conference cosponsors.)
ACSM is an association of 17,000 physicians, scientists and educators who have a professional interest in sports medicine and exercise science.
Twenty-four experts presented research papers and presentations from the perspectives of current evidence and research issues. A consensus panel (see Appendix 2 for panel members) composed of six experts in nutrition, epidemiology, medicine and sports and exercise science reviewed the evidence presented and formulated a consensus statement on the role of physical activity in obesity.
The College's official journal, Medicine & Science in Sports & Exercise, published the papers presented at the conference and consensus statement as a supplement, which is available online. Papers covered the extent of the obesity problem, the role of physical activity in the prevention and treatment of obesity and obesity-related conditions, and other topics.
The Consensus Panel concluded that:
- The prevalence of obesity is alarmingly high and increasing in the United States. More than half of the population (54.9 percent) is overweight or obese. Obesity is more common in African-American women, Mexican-American men and women, and people who are less educated or have lower incomes, than in other groups.
- Physical inactivity is common among large numbers of high school students. Two-thirds (63.8 percent) of high school students report vigorous activity three or more days weekly. Physical activity was higher among boys and, whites, and decreased with advancing grade.
- Less than a third (27.7 percent) of adults achieve moderate or vigorous levels of activity. Almost 30 percent report no regular physical activity outside of their work. Gender differences are less pronounced among adults than among youth.
- The direct costs of physical inactivity are estimated to be $24 billion a year, or 2.4 percent of U.S. health care expenditures. Physical inactivity and obesity combined account for 9.4 percent of national health care expenditures.
- The problems of overweight and obesity cannot be solved solely by instituting regimens of moderate exercise in the general population. The increase in energy expenditure from moderate exercise is insufficient to completely forestall weight gain with advancing age or reverse existing overweight or obesity.
- "Evidence suggests that a high level of physical activity can aid weight control either by improving the matching of food intake to energy expenditure or by raising expenditure so that it is difficult for people to eat themselves into a positive energy balance."
- Increased physical activity appears to have independent beneficial effects on medical conditions that accompany obesity, including diabetes and high cholesterol.
The Consensus Panel noted that a number of research needs remain, including the following:
- Researchers need improved methods of measuring physical activity and energy intake that are appropriate for population-based observational studies. Motion sensors appear to provide a reliable assessment of patterns of physical activity, but more study is needed. Questionnaires and food diaries offer notably poor measures of nutrient and energy intake.
- The fields of physical activity and exercise physiology are rich in observational studies that examine people and various characteristics at discrete moments in time. They are lacking in randomized controlled trials, which randomly assign participants to a treatment or comparison (control) group to assess the effectiveness of a given treatment or intervention.
- If the results of randomized controlled trials are to be convincing to the medical community, they must have sufficient sample size, duration and statistical power to yield a definitive result. The experimental groups should contain women, who have not been included in many previous studies, as well as men.
The Robert Wood Johnson Foundation (RWJF) provided $45,000 in grant support for the effort.
GRANT DETAILS & CONTACT INFORMATION
Publication on the Use of Physical Activity to Prevent and Treat Obesity and Its Co-Morbidities
American College of Sports Medicine Foundation (Indianapolis, IN)
Dates: January 1999 to December 1999
Jane Gleason Senior
M&M Mars, Inc.
Centers for Disease Control and Prevention
National Heart, Lung, and Blood Institute
National Institute of Child Health and Human Development
National Institute of Diabetes and Digestive and Kidney Diseases
North American Association for the Study of Obesity
Knoll Pharmaceutical Company
Consensus Panel Members
Scott Grundy, M.D., Ph.D., Chair
Center for Human Nutrition
University of Texas
George Blackburn, M.D.
Beth Israel Deaconess Medical Center
Millicent Higgins, M.D.
Department of Epidemiology
School of Public Health
University of Michigan
Ann Arbor, Mich.
Ronald Lauer, M.D.
University of Iowa
Division of Pediatric Cardiology
Iowa City, Iowa
Michael Perri, Ph.D.
University of Florida
Donna Ryan, M.D.
Pennington Biomedical Research Center
Baton Rouge, La.
(Current as of date of this report; as provided by grantee organization; not verified by RWJF; items not available from RWJF.)
Medicine & Science in Sports & Exercise (Supplement). "American College of Sports Medicine Roundtable: Physical Activity in the Prevention and Treatment of Obesity and Its Comorbidities." 31(November): S497S667, 1999. (Available online.)
- Astrup A. "Physical Activity and Weight Gain and Fat Distribution Changes with Menopause Issues."
- Blair S. "Effects of Physical Inactivity and Obesity on Morbidity and Mortality."
- Blair S and Bouchard C. "Physical Activity and Obesity: American College of Sports Medicine Consensus Conference."
- Blundell JE. "Physical Activity and Regulation of Food Intake."
- Bouchard C and Blair S. "Introductory Comments to the Consensus on Physical Activity and Obesity."
- Colditz GA. "The Economic Costs of Obesity and Inactivity."
- Di Pietro L. "Physical Activity in the Prevention of Obesity."
- Epstein LH. "Physical Activity in the Treatment of Childhood Overweight and Obesity."
- Fagard R. "Physical Activity in the Prevention and Treatment of Hypertension in the Obese."
- Flegal KM. The Obesity Epidemic in Children and Adults."
- Grundy S, Blackburn G, Higgins M, Lauer R, Perri MG and Ryan D. "Physical Activity in the Prevention and Treatment of Obesity and its Comorbidities."
- Hill JO, "Overview of the Determination of Overweight and Obesity."
- Jebb S. "Contribution of a Sedentary Lifestyle and Inactivity to the Etiology of Overweight and Obesity."
- Kelley DE and Goodpaster BH. "Physical Activity in the Prevention and Treatment of Impaired Glucose Tolerance and Hyperinsulinemia in the Obese."
- Pi-Sunyer X, "Co-Morbidities of Overweight and Obesity."
- Poehlman ET. "Physical Activity and the Progressive Change in Body Composition with Aging."
- Pratt M. "Levels of Physical Activity and Inactivity in Children and Adults in the United States."
- Rauramaa R and Väisänen S. "Physical Activity in the prevention and Treatment of a Thrombogenic Profile in the Obese."
- Rissanen A and Fogelholm M. "Physical Activity in the Prevention and Treatment of Other Morbid Conditions and Impairments Associated with Obesity."
- Ross R and Janssen I. "Is Abdominal Fat, Particularly Visceral Fat, Preferentially Mobilized when the Energy Deficit is Induced by Regular Physical Activity."
- Rössner S. "Physical Activity and Prevention and Treatment of Weight Gain Associated with Pregnancy."
- Saris W. Assessment of Physical Activity Level and Energy Expenditure of Activity."
- Seidell JC. "Overweight and Obesity in the Mortality Rate Data."
- Stefanick M. "Physical Activity in the Prevention and Treatment of the Dislipoproteinemia Associated with Obesity."
- Tremblay A. "Physical Activity and Preference for Selected Macronutrients: Activity and Macronutrient Preferences."
- Wing R. "Physical Activity in the Treatment of the Adulthood Overweight and Obesity."
"American College of Sports Medicine Roundtable: Physical Activity in the Prevention and Treatment of Obesity and Its Co-Morbidities," February 46, 1999, Indianapolis, Ind. Attended by approximately 30 participants representing diverse areas of scientific expertise. (For a list of presentations, see Reports, above.)
Report prepared by: Mary Nakashian
Reviewed by: Richard Camer
Reviewed by: Robert Narus
Program Officer: Karen S. Gerlach