Total-body electrical conductivity (TOBEC): relationship to estimates of muscle mass, fat-free weight, and lean body mass

A comparison of methods for estimating body composition (BC) of 12 subjects was made by using fat-free weight from total-body electrical conductivity (FFWT), muscle mass from 3-methylhistidine excretion (MM3MH) and creatinine excretion (MMCRE), fat-free weight from hydrostatic weighing (FFWBD), and lean body mass from whole-body potassium counting (LBMK). Data were analyzed for day-to-day variability and regression analyses were applied to compare the different methods of measuring BC. Mean values (+/- SEM, kg) for the estimates were 53.9 +/- 3.5 (FFWT), 26.9 +/- 2.9 (MM3MH), 25.3 +/- 2.5 (MMCRE), 53.2 +/- 3.6 (FFWBD), and 52.8 +/- 3.5 (LBMK). Regression analyses revealed that TOBEC estimates of fat-free weight had an adjusted r2 (+/- SEE, kg) of 0.95 +/- 2.2, 0.50 +/- 7.9, 0.95 +/- 1.8, and 0.88 +/- 4.0 for MM3MH, MMCRE, FFWBD, and LBMK, respectively. It was concluded that TOBEC is a potentially reliable method for estimating the muscle mass within the fat-free compartment, as well as fat-free weight and lean body mass.