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Original Investigation
June 9, 2003

Effects of a 16-Month Randomized Controlled Exercise Trial on Body Weight and Composition in Young, Overweight Men and Women: The Midwest Exercise Trial

Author Affiliations

From the Energy Balance Laboratory, Schiefelbusch Life Span Institute (Drs Donnelly, Jacobsen, and Washburn), and the Human Performance Laboratory (Dr Potteiger), University of Kansas, Lawrence; the Center for Human Nutrition (Dr Hill and Ms Sharp) and the Departments of Pediatrics (Drs Johnson and Sonko), Pediatrics and Pharmacology (Dr Fennessey), and Preventive Medicine and Biometrics (Dr Tran), University of Colorado Health Sciences Center, Denver; the Departments of Dietetics and Nutrition (Drs Sullivan and Hise), Preventive Medicine (Dr Mayo), and Internal Medicine (Dr Gibson) and the Kansas Cancer Institute (Dr Mayo), University of Kansas Medical Center, Kansas City; the Human Performance Laboratory, University of Nebraska–Kearney (Dr Heelan); the Physical Activity and Weight Management Research Center, University of Pittsburgh, Pittsburgh, Pa (Dr Jakicic); and the Cooper Institute for Aerobics Research, Dallas, Tex (Dr Blair). Dr Potteiger is now with the Human Performance Laboratory, Virginia Commonwealth University, Richmond. Dr Jakicic is a scientific advisor for Body Media, Pittsburgh, Pa, and CaloriesCount.com, Atlanta, Ga, and a board member for Intelligent Health Ltd, Carefree, Ariz. The remaining authors have no relevant financial interest in this article.

Arch Intern Med. 2003;163(11):1343-1350. doi:10.1001/archinte.163.11.1343

Background  In light of the current obesity epidemic, treatment models are needed that can prevent weight gain or provide weight loss. We examined the long-term effects of a supervised program of moderate-intensity exercise on body weight and composition in previously sedentary, overweight and moderately obese men and women. We hypothesized that a 16-month program of verified exercise would prevent weight gain or provide weight loss in the exercise group compared with controls.

Methods  This was a randomized controlled efficacy trial. Participants were recruited from 2 midwestern universities and their surrounding communities. One hundred thirty-one participants were randomized to exercise or control groups, and 74 completed the intervention and all laboratory testing. Exercise was supervised, and the level of energy expenditure of exercise was measured. Controls remained sedentary. All participants maintained ad libitum diets.

Results  Exercise prevented weight gain in women and produced weight loss in men. Men in the exercise group had significant mean ± SD decreases in weight (5.2 ± 4.7 kg), body mass index (calculated as weight in kilograms divided by the square of height in meters) (1.6 ± 1.4), and fat mass (4.9 ± 4.4 kg) compared with controls. Women in the exercise group maintained baseline weight, body mass index, and fat mass, and controls showed significant mean ± SD increases in body mass index (1.1 ± 2.0), weight (2.9 ± 5.5 kg), and fat mass (2.1 ± 4.8 kg) at 16 months. No significant changes occurred in fat-free mass in either men or women; however, both had significantly reduced visceral fat.

Conclusions  Moderate-intensity exercise sustained for 16 months is effective for weight management in young adults.