VALIDITY OF BMI-BASED BODY FAT EQUATIONS IN MEN AND WOMEN: A 4-COMPARTMENT MODEL COMPARISON

The purpose of this study was to compare body mass index (BMI)-based body fat percentage (BF%) equations and skinfolds with a 4-compartment (4C) model in men and women. One hundred thirty adults (63 women and 67 men) volunteered to participate (age = 23 +/- 5 years). BMI was calculated as weight (kg) divided by height squared (m(2)). BF% was predicted with the BMI-based equations of Jackson et al. (BMIJA), Deurenberg et al. (BMIDE), Gallagher et al. (BMIGA), Zanovec et al. (BMIZA), Womersley and Durnin (BMIWO), and from 7-site skinfolds using the generalized skinfold equation of Jackson et al. (SF7(JP)). The 4C model BF% was the criterion and derived from underwater weighing for body volume, dual-energy X-ray absorptiometry for bone mineral content, and bioimpedance spectroscopy for total body water. The constant error (CE) was not significantly different for BMIZA compared with the 4C model (p = 0.74, CE = -0.2%). However, BMIJA, BMIDE, BMIGA, and BMIWO produced significantly higher mean values than the 4C model (all p < 0.001, CEs = 1.8-3.2%), whereas SF7(JP) was significantly lower (p < 0.001, CE = -4.8%). The standard error of estimate ranged from 3.4 (SF7(JP)) to 6.4% (BMIJA) while the total error varied from 6.0 (SF7(JP)) to 7.3% (BMIJA). The 95% limits of agreement were the smallest for SF7(JP) (+/- 7.2%) and widest for BMIJA (+/- 13.5%). Although the BMI-based equations produced similar group mean values as the 4C model, SF7(JP) produced the smallest individual errors. Therefore, SF7(JP) is recommended over the BMI-based equations, but practitioners should consider the associated CE.