Comparison of hydrostatic weighing to bioelectrical impedance analysis in women greater than thirty percent body fat

Abstract

Twenty-five female Ss age 18-65 years who had participated in a community weight loss class volunteered to have their body composition determined via hydrostatic weighing (HW) and bioelectrical impedance analysis (BIA), All subjects were greater than 30% body fat. It was discovered that bioelectrical impedance analysis using the BES 200Z analyzer significantly (p<.05) underpredicted percent fat in all 25 subjects, compared to HW. Percent fat predicted using the BES 2002 analyzer was poorly correlated (r - .59) to percent fat using HW. Mean percent fat determined by BIA was 33.9 +/- 6.39 compared to 42.8 +/- 6.30 using HW. Mean fat free mass (FFM) was significantly overestimated (p<.05) using BIA (54.8 + 6.89) compared to HW (44.1 + 6.80). New prediction equations were developed for the impedance analyzer. The highest correlation for a developed prediction equation was r - .97. This equation predicted FFM using the variables height squared (ht2), weight, age, impedance (R), and waist-to-hip ratio (WHR). Further investigation needs to be done to validate the accuracy of this equation for the BES 200Z analyzer.