Validity of methods of body composition assessment in young and older men and women

We examined the validity of percent body fat (%Fat) estimation by two-compa rtment (2-Comp) hydrostatic weighing (Siri 2-Comp), S-Comp dual-energy X-ra y absorptiometry (DEXA S-Comp), 3-Comp hydrostatic weighing corrected for t he total body water (Siri 3-Comp), and anthropometric methods in young and older individuals (n = 78). A 4-Comp model of body composition served as th e criterion measure of %Fat (Heymsfield 4-Comp; S. B. Heymsfield, S. Lichtm an, R. N. Baumgartner, J. Wang, Y. Kamen, A. Aliprantis, and R. N. Pierson Jr., Am. J. Clin. Nutr. 52: 52-58, 1990.). Comparison of the Siri S-Comp wi th the Heymsfield 4-Comp model revealed mean differences of less than or eq ual to 0.4 %Fat, r values greater than or equal to r = 0.997, total error v alues less than or equal to 0.85 %Fat, and 95% confidence intervals (Bland- Altman analysis) of less than or equal to 1.7 %Fat. Comparison of Siri 2-Co mp, DEXA, and anthropometric models with the Heymsfield 4-Comp revealed tha t total error scores ranged from +/-4.0 to +/-10.7 %Fat, and 95% confidence intervals associated with the Bland-Altman analysis ranged from +/-5.1 to +/-15.0 %Fat. We conclude that the Siri S-Comp model provides valid and acc urate body composition data when compared with a 4-Comp criterion model. Ho wever, the individual variability associated with the Siri 2-Comp, DEXA 3-C omp, and anthropometric models may limit their use in research settings. Th e use of anthropometric estimation methods resulted in large mean differenc es and a considerable amount of interindividual variability. These data sug gest that the use of these techniques should be viewed with caution.