Reference values of fat-free and fat masses by bioelectrical impedance analysis in 3393 healthy subjects

Determination of fat-free mass (FFM) and fat mass (FM) is of considerable i nterest in the evaluation of nutritional status. In recent years, bioelectr ical impedance analysis (BIA) has emerged as a simple, reproducible method used for the evaluation of FFM and FM, but the lack of reference values red uces its utility to evaluate nutritional status. The aim of this study was to determine reference values for FFM, FM, and %FM by BIA in a white popula tion of healthy subjects, to observe the changes in these values with age, and to develop percentile distributions for these parameters. Whole-body re sistance of 1838 healthy white men and 1555 women, aged 15-64 y, was determ ined by using four skin electrodes on the right hand and foot. FFM and FM w ere calculated according to formulas validated for the subject groups and a nalyzed for age decades. This is the first study to present BIA-determined age- and sex-specific percentiles for FFM, FM, and %FM for healthy subjects , aged 15-64 y. Mean FM and %FM increased progressively in men and after ag e 45 y in women. The results suggest that any weight gain noted with age is due to a gain in FM. In conclusion, the data presented as percentiles can serve as reference to evaluate the normality of body composition of healthy and ill subject groups at a given age. Nutrition 2000;16:245-254. (C)Elsev ier Science Inc. 2000.