Prediction of visceral fat area in Japanese adults: proposal of prediction method applicable in a field setting

Objective: This study aimed to develop a prediction equation for the visceral fat area at the umbilical level (VFA(L4-5)) in Japanese adults, using internal fat mass (IFM) estimated from a few anthropometric variables. Methods: Subjects were 112 adults aged from 25 to 82 years (body mass index (BMI)=24.2+/-3.1 kg/m², ranged from 15.7 to 31.2 kg/m²). Another 60 adults aged from 21 to 71 years were recruited for the crossvalidation group (BMI=24.5+/-4.0 kg/m², ranged from 17.1 to 34.6 kg/m²). We examined (1) the prediction of IFM based on a small number of skinfold thicknesses; (2) the prediction of VFA(L4-5) using IFM and (3) the application of bioelectrical impedance analysis (BIA) measurement. VFA(L4-5) was measured by computed tomography (reference value). Total fat mass was measured by dual-energy X-ray absorptiometry (DXA) and single-frequency BIA with 8-point tactile electrodes. Results: Three skinfolds at the abdomen, side chest and suprailiac were selected to estimate IFM. From IFM estimated using these three skinfolds, waist-to-hip ratio (WHR), sex and age, about 75% of the variance of VFA(L4-5) could be explained (Eq(VFA1): R=863, R²=0.745, standard error of estimate (s.e.e.)=20.483 cm²). When substituting IFM based on BIA measurement (IFM(BIA)) into Eq(VFA1), there were no significant mean differences from the reference in both equations, and high correlations were found (r=0.860, s.e.e.=20.902 cm²), although a significant mean difference in total fat mass was found between DXA and BIA measurements. The prediction equation using IFM(BIA) (Eq(VFA2)) could have prediction accuracy comparable with that of Eq(VFA1) (Eq(VFA2): R=879, R²2=0.773, s.e.e.=20.324 cm²). Furthermore, when applying these equations to the crossvalidation group, there were cross-validity in both equations. Conclusion: This study proposed a prediction equation for VFA(L4-5) from WHR and IFM based on three skinfolds, and the validity of BIA measurement in Japanese adults. We can propose the procedure for a field setting.