The prevalence of overweight or obesity in black women in the USA (66%) is 1.4 times that of white women (47%). In a study of white and black women who lost 16% of their body weight by dieting alone, the black women's energy expenditure remained significantly lower than their white counterparts after dieting. Following weight loss, both groups of dieters realized notable improvements in aerobic capacity and recovery rate after exercise, making it easier for them to follow an exercise program and retain the loss. However, the black women's persistently lower energy expenditure rate may make them more prone to regain the weight.
Weinsier et al. conducted the study at a University of Alabama clinic with 19 black and 18 white overweight female volunteers. Over 24 weeks, all of the subjects successfully reached a normal body weight (defined as a Body Mass Index of less than 25), by following a regimen in which all meals were provided by the clinic's research kitchen.
While both groups of dieters improved their exercise capacity, black women had a substantially lower energy expenditure while sleeping, at rest, during normal physical activity, and while exercising. On average their energy expenditure was 11.7% less than white women's.
According to the authors, the differences in body composition between black and white women may provide possible explanations for discrepancies in energy expenditure. Black women have denser bones than white women, and more lean issue in the limbs than in the trunk. The authors suggest that the lower proportion of metabolically active organ tissue in the trunk could account for the lower rates of energy expenditure among black women.
Weinsier R L, et al. Energy expenditure and free-living physical activity in black and white women: comparison before and after weight loss. Am J Clin Nut 2000;71:1138-1146.
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