Development of a new method for estimating visceral fat area with multi-frequency bioelectrical impedance.

Excessive visceral fat area (VFA) is a major risk factor in such conditions as cardiovascular disease. In assessing VFA, computed tomography (CT) is adopted as the gold standard; however, this method is cost intensive and involves radiation exposure. In contrast, the bioelectrical impedance (BI) method for estimating body composition is simple and noninvasive and thus its potential application in VFA assessment is being studied. To overcome the difference in obtained impedance due to measurement conditions, we developed a more precise estimation method by selecting the optimum body posture, electrode arrangement, and frequency. The subjects were 73 healthy volunteers, 37 men and 36 women, who underwent CT scans to assess VFA and who were measured for anthropometry parameters, subcutaneous fat layer thickness, abdominal tissue area, and impedance. Impedance was measured by the tetrapolar impedance method using multi-frequency BI. Multiple regression analysis was conducted to estimate VFA. The results revealed a strong correlation between VFA observed by CT and VFA estimated by impedance (r = 0.920). The regression equation accurately classified VFA > or = 100 cm(2) in 13 out of 14 men and 1 of 1 woman. Moreover, it classified VFA > or = 100 cm(2) or < 100 cm(2) in 3 out of 4 men and 1 of 1 woman misclassified by waist circumference (W) which was adopted as a simple index to evaluate VFA. Therefore, using this simple and convenient method for estimating VFA, we obtained an accurate assessment of VFA using the BI method.