VALIDITY OF SELECTED BIOIMPEDANCE EQUATIONS FOR ESTIMATING BODY COMPOSITION IN MEN AND WOMEN: A FOUR-COMPARTMENT MODEL COMPARISON.

The purpose of this study was to compare body fat percentage (BF%) and fat-free mass (FFM) values from bioelectrical impedance analysis (BIA) equations to values determined from a 4-compartment (4C) model. Eighty-two adults (42 men and 40 women) volunteered to participate (age = 23 ± 5 years). Body fat percentage and FFM were estimated from previously developed BIA equations by Chumlea et al. (BIA_CH), Deurenberg et al. (BIA_DE), Kyle et al. (BIA_KYLE), and Sun et al. (BIA_SUN). Four-compartment model body composition was derived from underwater weighing for body density, dual-energy X-ray absorptiometry for bone mineral content, and bioimpedance spectroscopy for total body water. The standard error of estimate (SEE) for group BF% and FFM ranged from 3.0 to 3.8% and 2.1 to 2.7 kg, respectively. The constant error (CE) was significantly higher and lower for BF% and FFM (p < 0.001), respectively, for 3 BIA equations (BIA_CH, CE = 3.1% and -2.2 kg; BIA_DE, CE = 3.7% and -2.9 kg; BIA_KYLE, CE = 2.3% and -1.9 kg), but was not significant for BF% (p = 0.702) and FFM (p = 0.677) for BIA_SUN (CE = -0.1% and 0.1 kg). The 95% limits of agreement were narrowest for BIA_CH (±5.9%; ±4.2 kg) and largest for BIA_DE (±7.4%; ±6.2 kg). The significant CE yielded by BIA_CH, BIA_DE, and BIA_KYLE indicates these equations tend to overpredict group BF% and underestimate group FFM. However, all BIA equations produced low SEEs and fairly narrow limits of agreement. When the use of a 4C model is not available, practitioners might consider using one of the selected BIA equations, but should consider the associated CE. [ABSTRACT FROM AUTHOR]