Resting Energy Expenditure in Obese African American and Caucasian Women

Abstract

The prevalence of obesity among African American women approaches 50% and greatly exceeds rates for Caucasian women. In addition, black women lose less weight than white during obesity treatment and gain more weight when untreated. This study assessed resting energy expenditure (REE) and body composition in obese white (n=122) and black (n=44) women to explore the relationship between biological variables and these observed differences. REE and body composition were assessed by indirect calorimetry and densitometry, respectively, before weight loss. REE was significantly lower in black subjects (1637.6 ± 236.9 kcal/d) than in white (1731.4 ± 262.0) (p=0.04). REE remained significantly lower in blacks than whites after adjusting for body weight (p=0.02). REE, adjusted for fat-free mass, was also significantly lower in blacks than whites (p<0.0001), although the overestimation of fat-free mass by densitometry in blacks may have contributed to this finding. There were no differences between the groups in respiratory quotient. These results suggest that a decreased REE may exist in obese black women, and it may be related to the observed differences between black and white women in the prevalence of obesity and in the response to weight loss treatment. These crosssectional findings await confirmation in longitudinal studies.