VALIDITY OF SIX BODY COMPOSITION METHODS IN ADOLESCENT BOYS

Abstract

A number of novel methods of estimating body fatness are particularly suitable for pediatric use, and have become popular. However, their validity is unknown at present. PURPOSE The present study aimed to assess the validity of 6 methods against a reference (3-component model) in adolescent males. METHODS In 42 healthy boys age 10–14 years we measured body fatness by a reference method (3 component model based on body density and total body water, TBW). We estimated fatness simultaneously in these subjects by the following 6 METHODS hand-foot impedance (BODYSTAT): leg-leg impedance (TANITA); body density using Lohmans constants for density of fat-free mass (FFM); BODPOD using the manufacturers software; skinfolds (Slaughter equations); TBW using Lohmans constants for hydration of FFM. Agreement with the reference was assessed by calculation of biases and limits of agreement. RESULTS Estimates of fatness from TBW had the smallest bias and narrowest limits of agreement relative to the reference method. For TBW bias was +0.5 kg (limits of agreement 2.9 kg), with mean fat mass of 8.7 kg. Biases were much greater, and limits of agreement wider, for all the other methods. Accuracy at the level of the individual child was poor. CONCLUSION Currently available field and laboratory methods for estimation of body composition in adolescent boys are not valid. For applications where high accuracy is essential, this can only be achieved by use of reference methods.