Evaluating the contribution of differences in lean mass compartments for resting energy expenditure in African American and Caucasian American children

BACKGROUND Resting energy expenditure (REE), adjusted for total lean mass (LM), is lower in African American (AA) than Caucasian American (CA) children. Some adult studies suggest that AA-CA differences in lean mass compartments explain this REE difference. Similar data are limited in children. OBJECTIVE To evaluate differences in compartment-specific lean mass between AA and CA children and examine the individual contributions of high-metabolic rate-at-rest trunk lean mass (TrLM) and low-metabolic-rate-at-rest appendicular lean mass (AppLM) for AA-CA differences in REE. METHODS We studied a convenience sample of 594 AA (n = 281) and CA (n = 313) children. REE was measured by using indirect calorimetry; dual-energy X-ray absorptiometry was used to assess body composition. ANCOVAs were performed to examine AA-CA differences in TrLM, AppLM and REE. After accounting for age, sex, height, pubertal development, bone mass and adiposity, REE was evaluated adjusting for total LM (model A) and separately adjusting for TrLM and AppLM (model B). RESULTS African American children had greater adjusted AppLM (17.8 ± 0.2 [SE] vs. 16.0 ± 0.2 kg, p