Regional lean body mass and resting energy expenditure in non-obese adults

Objective To study the effect of regional lean body mass (LBM) on resting energy expenditure (REE). Design Cross-sectional study in a homogenous group of 26 young healthy non-obese subjects. Methods Regional body composition was assessed by dual-energy X-ray absorptiometry (DEXA). REE was measured by indirect calorimetry. Results REE showed positive relationships with whole body LBM (LBMb; r=0.89) as well as with regional LBM (LBMtrunk = LBMt, r = 0.88, and LBMarms+legs = LBMe for LBMextremities, r = 0.89) with non-zero intercepts (between 1.86 and 2.83 MJ/d). REE per kg LBMb falls as LBMb increases (r 0.77). By contrast, REE adjusted for regional distribution of LBM (i. e. the ratio of LBMt to LBMe) increases as LBMb increases (r = 0.91) showing a near-zero intercept (i.e. 0.048 MJ/d). Adjusting REE for LBMb as well as for the ratio of LBMt to LBMe can be used for comparison between subjects. Conclusions Our data suggest that regional distribution of LBM is a determinant of REE. Assessment of LBMt and LBMe by DEXA provides a possibility to adjust for the nonlinearity of REE on LBMb.