Lean-body-mass composition and resting energy expenditure before and after long-term overfeeding

This report deals with the association between the constituents of lean body mass (LBM) and resting metabolic rate (RMR) before and after a 100-d overfeeding period. Computed-tomography (CT) scans of 22 young adult males at nine different body levels were used to estimate adipose tissue mass (ATMct), LBMct, skeletal-muscle mass (SMMCT), and non-muscular LBMct (NM-LBMCT). Before overfeeding, all body constituents, except ATMct, were significantly correlated with RMR. Only body mass changes were significantly correlated with RMR changes. Comparison of these results with those of several studies in the literature reveals that the relationship between RMR and fat-free mass is highly influenced by the size of the SD for the latter variable. In stepwise-multiple-regression analysis, only SMMct could be used to predict RMR. It was concluded that SMMct and ATMct, but not NM-LBMct, increased during overfeeding and that the best correlates of RMR remain LBMct, SMMct, and body mass.