Estimation of minimal weight of adolescent males using multicomponent models

The purpose of this study was to determine whether the estimation of minimal weight (the body weight at which 5% of the weight is fat) of adolescent males could be improved by accounting for differences in hydration state and bone mineral content. Improvement was defined as a larger value for minimal weight and a smaller standard deviation compared to minimal weight estimated from body density. Forty adolescent males (mean age +/- SD, 15.5 +/- 1.4 yr) were measured for height, weight, body density (hydrostatic weighing), total body water (deuterium oxide dilution), and bone mineral content (single photon absorptiometry). Twenty-two adult males (mean age +/- SD, 23.6 +/- 2.2 yr) were measured as a reference group. Percent body fat and minimal weight were calculated from the body density (MWD), body density adjusted for total body water (MWDW), and body density adjusted for body water and bone mineral content (MWDWB). Repeated-measures ANOVA was used to test for differences between the methods and for trends in the data. The results showed a slight but nonsignificant increase in minimal weight for the adolescent group when body water and bone mineral data were added. The means +/- SD for MWD, MWDW, and MWDWB values of the adolescents were 54.6 +/- 9.0 kg, 54.8 +/- 8.6 kg, and 55.4 +/- 8.4 kg, respectively. It was concluded that the multicomponent methods, which accounted for hydration and bone mineral status, did not significantly improve the estimates of minimal weight of adolescent males compared to the single component method, i.e., minimal weight from body density.