Changes in resting energy expenditure after weight loss in obese African American and white women

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Abstract
Background: Previous studies showed that resting energy expenditure (REE) is lower in obese African American women than in obese white women. It is unknown, however, whether there are racial differences in how REE responds to weight loss and energy restriction. Objective: We assessed REE, body composition, and respiratory quotient before and after weight loss in obese black and white women. Design: We measured REE by indirect calorimetry and body composition by densitometry before and after 20–24 wk of treatment with a 3870–4289-kJ/d diet. Subjects were 109 obese females (24 black, 85 white) with a mean (±SD) body mass index (in kg/m2) of 36.3 ± 5.0, weight of 95.7 ± 12.6 kg, and age of 42.3 ± 8.1 y. Results: Before treatment, REE, adjusted for body composition, was significantly lower in black than in white subjects (P = 0.001). Black subjects lost significantly less weight during treatment than did white subjects (13.4 ± 5.9 kg or 14.2 ± 5.7% compared with 16.4 ± 5.6 kg or 17.0 ± 5.7%, respectively; P = 0.04). Analyses that controlled for initial REE and changes in fat mass and fat-free mass showed that blacks had significantly greater decreases in REE after treatment than did whites (9.9 ± 7.3% compared with 6.3 ± 7.4%; P = 0.02). Conclusion: This study suggests that weight loss results in greater reductions in REE in obese black women than in obese white women. These data underscore the need to consider both biological and behavioral factors when setting expectations and assessing outcomes for obesity treatment in African American women.