Objective: The purpose of this study was to examine differences in both resting energy expenditure (REE) and respiratory quotient (RQ) between overweight African-American and Caucasian women of comparable age and body mass index (BMI).
Design: Cross-sectional.
Subjects: REE was assessed in 41 women (22 African-American and 19 Caucasian) who were recruited to participate in this study. The African-American women were aged 36.4+/-5.7 y with a BMI of 32.6+/-5.4 kg/m2, and the Caucasian women were aged 35.4+/-5.7 y with a BMI of 31.3+/-3.4 kg/m2.
Measurements: Body composition was assessed using dual energy x-ray absorptiometry (DEXA). REE was assessed via the dilution technique following an overnight fast.
Results: REE was lower in African-Americans (7279+/-825 kJ/d) compared to Caucasians (7807+/-854 kJ/d) (P = 0.051). Analysis of covariance showed that REE remained significantly lower in African-American women after correcting for body weight and lean body mass. There was no effect of ethnicity on RQ.
Conclusion: These results indicate that there is a significant difference in REE between Caucasian and African-American overweight women. This difference in REE may contribute to the higher rates of obesity found in the African-American population. This difference may also partially explain the smaller weight losses typically seen in African-American women when compared to Caucasian women enrolled in a weight loss program.