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 non-linearity of REE on LBMb.