USE OF THE BIOELECTRICAL IMPEDANCE METHOD IN ASSESSING BODY COMPOSITION CHANGES IN OBESE WOMEN 1382

Abstract

The purpose of this study was to determine the validity of bioelectrical impedance (BIA) (TANITA Body Fat Analyzer-Model TBF 105, TANITA Corporation of America, Inc.; Skokie, Illinois) as a method of estimating body composition(BC) when compared to hydrostatic weighing (HW) in an obese population. Fifty-three obese women (43±0.7% fat, 47.3±1.3 yrs) and 15 age matched controls (26.1±1.7% fat, 47.1±2.9 yrs) were studied. The obese subjects were randomly divided into 1 of 4 groups, with BC measurements made pre- and post-12 week intervention: Diet (D) alone (1,200 kcal/day), exercise (E) alone (five 45 min sessions/wk at 78.4±0.6% max HR), both diet and exercise (DE) and controls (C) (no diet or exercise). Lean body mass(LBM), fat mass (FM) and body fat (BF) were estimated from BIA and HW. For all subjects combined, estimation of BF by BIA and HW was highly correlated(r=0.90, p<0.001). Mean values for BF were significantly different between HW and BIA (43.9±0.7% and 48.6±1.2%, p<0.05), respectively. When comparing DE and C, the change in BF over time was significantly higher when using BIA (8.2±0.9%) compared to HW (4.6±0.5%). In summary, cross sectionally, a high correlation was found between BIA and HW in estimating BF; however, BIA tended to overestimate BF in obese women by 4.7±1.3%. In addition, BIA tended to overestimate changes in BF across time in a dieting obese population.