A new simple method for the measurement of visceral fat accumulation by bioelectrical impedance.

W e and others (1–9) have shown that the accumulation of visceral fat is associated with multiple risk factor syndrome more closely than with the BMI itself or the amount of subcutaneous fat. In these studies, computed tomography (CT) scan at the umbilical level (10) was used for the assessment of visceral fat area (VFA). However, the method is not cost-effective and/or radiation exposure is problematic; thus, it is often unsuitable for screening large groups of individuals. There is a need for a simple and noninvasive method to assess visceral fat accumulation. The bioelectrical impedance analysis (BIA) method, which is based on the electric resistance difference between the fat and components of other organs (11–14), should meet this need. Conventional BIA approaches have estimated total fat content but not regional fat distribution (11– 13). Recently, attempts to assess the amount of abdominal subcutaneous fat by the local BIA method were reported (14). Here, we developed a new technique to specifically evaluate VFA by using the abdominal BIA method. RESEARCH DESIGN AND METHODS — The study subjects were 59 healthy volunteers and 32 inpatients with suspected cardiovascular disease at Osaka University Hospital. Waist circumference (Wc) at the umbilical level was measured in the late exhalation phase while standing. All subjects underwent the abdominal BIA method to estimate VFA. The voltage occurring at the flank to the flow of current between the umbilicus and the back correlates significantly with VFA and is unaffected by subcutaneous fat area. The voltage becomes larger as visceral fat accumulates even in the subjects with the same Wc because the electric resistance of intra-abdominal fat is greater than that of fat-free mass, and the density of the equipotential lines between two electrodes becomes denser (15) (Fig. 1A). The voltage correlates with the ratio of VFA to the total cross-sectional area of the abdomen, which can be approximated by using Wc (Fig. 1B). Thus, the VFA can be expressed as