Public Release: 

Lower Metabolic Rates May Make It Harder For Black Women To Lose Weight

University of Pennsylvania School of Medicine

At rest, overweight African American women burn fewer calories than overweight Caucasian women, according to a study by researchers at the University of Pennsylvania Medical Center. The findings -- published in the most recent issue* of Obesity Research -- are among the first to suggest that biological factors may be partly responsible for higher rates of obesity in black women. Statistics show nearly 50% of black women are overweight, compared to 33% of white women. In addition, black women tend to lose less weight than white women in weight control programs. "Although environmental factors such as diet, physical activity, and cultural preferences of body shapes are important, biological factors should be considered when trying to understand weight and weight loss in black women," says lead author Gary D. Foster, PhD, clinical director of Penn's Weight and Eating Disorders Program.

The investigators measured the resting metabolic rate of 166 women (44 black, 122 white) who weighed an average of 224 pounds. (Resting metabolic rate is the number of calories burned at rest, and makes up two-thirds of all the energy burned in one day.) The resting metabolic rate of black women was nearly 100 calories per day less than that of white women. The difference was still apparent after adjusting for weight and muscle mass. The results suggest a partial biological explanation for the increased weight and smaller weight losses among black women.

Similar to findings in a variety of ethnic groups, this study confirms the important role of biological factors in the regulation of body weight. "We hope these findings can help overweight black women and their doctors appreciate the many factors that affect weight loss," says Dr. Foster. Although low metabolism may make weight loss more difficult, Penn researchers encourage obese black women to make small changes in diet and physical activity which will reduce body weight and improve health.

*Vol. 5, No.1, January, 1997: Published March 3, 1997

The University of Pennsylvania Medical Center's sponsored research ranks fifth in the United States, based on grant support from the National Institutes of Health, the primary funder of biomedical research in the nation -- $149 million in federal fiscal year 1996. In addition, for the second consecutive year, the institution posted the highest growth rate in its research activity -- 9.1 percent -- of the top ten U.S. academic medical centers during the same period. Penn news releases are available to reporters by direct e-mail, fax, or U.S. mail, upon request. They are also posted electronically to EurekAlert! (, an Internet resource sponsored by the American Association for the Advancement of Science, and to the SciNews-MedNews section of the Journalism Forum, a component of CompuServe. Additionally, they are distributed via the electronic news service Quadnet.


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