[Possibilities for determining body composition of man in relation to obesity]

The following methods for determining the body composition of obese individuals were compared: hydrostatic weighing; determination of total body water (distribution of antipyrine and of tritium oxide); determination of the total potassium content of the body; determination of the amount of excreted creatinine. The values for body fat which derived from the body density, from the total potassium content and from the distribution of antipyrine differed only to a small extent. These differences were not significant. But the value based on tritium oxide distribution differed significantly. The study of the body composition of obese individuals has clearly shown that the increase in body weight is significantly correlated with the increase in the proportion of fat in the body (r=0.444), with the increase in the absolute fat content (r=+0.898) and also with the increase in the proportion of lean body mass (r=0.826). Not only the fat (61.2%) but also the lean body mass (38.8%) contributes to the weight increase of obese individuals. The quantitative determination of the fat content of the body and of the fat-free substance not only serves to specify the diagnosis of obesity (in particular, it permits to detect the so-called latent obesity) but is also the basis of the assessment of certain function, e.g., energy metabolism. The effectiveness of different methods for losing weight may be evaluated by repeated determinations of the fat content and for the lean body mass.