Energy expenditure and substrate oxidation in White and African American young adults without obesity.

Abstract

It has been hypothesized that the increased risk of obesity among African Americans may be partially explained by low energy expenditure (EE) and impaired fat oxidation. Twelve White adults without obesity were pair-matched by age, sex and body mass index (BMI) to a sample of 12 African Americans. Resting EE (REE), 24-h EE, 24-h RQ, Sleep EE, Sleep RQ and spontaneous physical activity were measured in a respiratory chamber; and free-living total daily EE (TDEE) and physical activity EE were measured using doubly labeled water. There were no race differences in age, body composition, 24-h RQ, sleep RQ, or spontaneous or free-living physical activity; however, Whites had significantly higher REE (p=0.02), 24-h EE (p=0.02), Sleep EE (p=0.005); but not TDEE (p=0.30) compared to African Americans after adjustment for FFM. African Americans may have a higher risk for obesity because of lower energy expenditure.