Ability of new octapolar bioimpedance spectroscopy analyzers to predict 4-component-model percentage body fat in Hispanic, black, and white adults

Abstract

Background: New, vertical, 8-electrode bioimpedance spectroscopy (BIS) analyzers provide detailed body-composition and nutritional information within 2 min. This is the first report on BIS's accuracy in predicting relative fatness [percentage body fat (%BF)] in a heterogeneous sample according to a multicomponent model criterion. Objective: We compared %BF measurements from 2 BIS devices with those from a multicomponent model in a sample of Hispanic, black, and white adults. Design: Equal numbers of apparently healthy men and women (n = 75 of each) from each racial-ethnic group, diverse in body mass index and age, volunteered. Reference %BF (%BF4C) was computed by using a 4-component (4C) model with total bone mineral content obtained from dual-energy X-ray absorptiometry, body density from underwater weighing with measured residual lung volume, and total body water from traditional BIS. Estimations from InBody 720 (%BF720) and InBody 320 (%BF320) BIS analyzers were validated against %BF4C. Results: The %BF 720 (r = 0.85, SEE = 5.19%BF) and %BF320 (r = 0.84, SEE = 5.17%BF) correlations were significant (P < 0.05) in the men; main effects were nonsignificant. Correlations for %BF720 (r = 0.88, SEE = 4.85%BF) and %BF320 (r = 0.89, SEE = 4.82%BF) also were significant in the women (P < 0.05); there was a main effect for method but not race-ethnicity. There were no sex-specific overestimations or underestimations at the extremes of the distributions. Conclusions: BIS estimates of %BF 4C were well correlated in men and women. There were no significant methodologic differences in the men. The %BF4C was significantly underestimated by %BF720 and %BF320 in the women. © 2008 American Society for Nutrition.