DETERMINATION OF TOTAL BODY FAT BY ABSORPTION OF AN INERT GAS; MEASUREMENTS AND RESULTS IN NORMAL HUMAN SUBJECTS *

Abstract

The usefulness of the concept of a "fat-free lean mass" (FFLM)l has been widely appreciated (2)(3)(4)(5)(6).Such a concept involves a consideration of the mammalian body as a sum of two major components: a) the body fat, which varies widely from individual to individual and which may also vary in a given individual from time to time de- pending upon his state of nutrition; and b) the FFLM which is of relatively constant weight in a given healthy individual and of relatively constant composition in the various mammalian species ex- cept perhaps for the proportion of bone.Since the concentrations of protein, water and electro- lytes in the FFLM vary only slightly, it is the dif- ference in fat content which leads to wide variations in these concentrations in the whole body.This observation was made for individual tissues in 1937 by Hastings and Eichelberger (7).A knowledge of the relative proportions of these two major components of the body is of obvious biological interest.It has been suggested that the FFLM, rather than body weight or surface area, should be used as a primary reference standard for various purposes (8,9).Similarly, total body fat would seem to be fundamentally involved in the action and distribution of various substances