A longitudinal study of resting energy expenditure relative to body composition during puberty in African American and white children

Background: Body composition and resting energy expenditure (REE) have not been examined longitudinally during puberty. Objective: The purpose of this longitudinal study was to examine the influe nce of pubertal maturation on REE relative to body composition in African A merican and white children. Design: The study included 92 white and 64 African American children (mean age at baseline: 8.3 and 7.9 y, respectively) from Birmingham, AL. The chil dren had 2-5 annual measurements of fat mass (FM), lean mass (LM), and REE. The Tanner stages of the children ranged from 1 to 5. Mixed-model repeated -measures analyses were used to test the change in REE relative to body com position with increasing Tanner stage among ethnic and sex groups. Results: LM increased from Tanner stage 1 to subsequent stages. FM relative to LM decreased from Tanner stage 1 to stages 3, 4, and 5 but not from sta ge 1 to stage 2. The African American children had relatively higher limb L M and lower trunk LM than did the white children. REE declined with Tanner stage after adjustment for ethnicity, sex, FM, and LM. This decline was sig nificant from Tanner stage 1 to stages 3, 4, and 5 but not to Tanner stage 2. After adjustment for age, Tanner stage, FM, and LM or LM distribution, R EE was significantly higher in white than in African American children (by approximate to 250 kJ/d). Conclusion: In a large sample of children at various Tanner stages, we foun d an ethnic difference in REE after adjustment for age, Tanner stage, FM, a nd LM that was not explained by the difference in LM distribution.