Bioelectrical-impedance analysis as a measure of body composition in a West Indian population.

Percent body fat (%BF) was estimated in 50 males and 50 females aged 8-21 y by using hydrodensitometry (%BFd) and a bioelectrical-impedance analyzer (%BF-BIA). The sample population was racially heterogeneous, though predominantly of African origin. Percent body fat was computed from density by using an equation derived specifically for blacks. The BIA predicted %BF with r2 = 0.77 (SEE = 3.7%BF), underestimating by a mean of 1.7%BF. Residuals (%BFd - %BF-BIA) were normally distributed but were significantly correlated with age (P less than 0.01), although this effect was small. The theoretical bases for impedance analysis and for hydrodensitometry would appear for different reasons to impair applicability of these techniques to the present population and age group. However, for our population sample the BIA estimated %BF as precisely as other simple techniques applied to other populations.