Since in the U.S. obesity is more prevalent in African American (B) than in Caucasian (W) women, we examined differences in the RMR in these two groups. 19 w and 21 B obese, weight stable (BMI range 28-49), premenopauaal (age range 26-49), healthy, nondiabetic, sedentary women, had RMR measured by indirect calorimetry 3 times within a 2 week period. Fat free mass (FFM) vas measured by DEXA, by hydrodensitometry (UWW), by a four compartment model (4C, correcting for total body water and total body bone mineral) and by TBK counting. Aerobic fitness was measured by a submaxima] exercise test and body fat distribution by magnetic resonance imaging. The B and W women were not different with regard to age ( 36±1 vs 34±1 y), VO,max ( 20±1 vs 21±1 ml/Kg/min), BMI (35±1 vs 35±1), fat mass (FM, 43±2 vs 44±2 Kg, by DEXA), FFM (52±2 vs 50±2 Kg, by DEXA) and visceral fat area (110±11 vs 121±13 cm2) . For each group, the RMR (mean of the 3 measured values) was predicted by FFM (by DEXA, r = 0.74, p < 0.1×10-6 for B women and r = 0.78, p < 0.1×10-6 for w women) and not by age, vo2max, FM or body fat distribution variables. The slopes of the prediction equations were parallel for the two groups. After adjusting for FFM, the B women had significantly lower RMR than the W women (-125 Kcal/24 hr. , p < 0.005 by ANCOVA) . The same analysis, adjusting for FFM calculated from 3 other body composition methods ; FFM by UWW, FFM by 4C and using absolute TBK content (in mEq) as a surrogate for active FFM each showed the B women having significantly lower RMR than the W women. The lower RMR adjusted for FFM in B as compared to W women may partly explain the higher prevalence of obesity in the former over the latter.
|Original language||English (US)|
|State||Published - Dec 1 1996|
All Science Journal Classification (ASJC) codes
- Molecular Biology