Why are associations with health risks better for waist circumference than for visceral adipose tissue? A mechanistic explanation (391.5)

Abstract

Visceral adipose tissue (VAT) is strongly associated with health risks, although an anomalous finding is that VAT‐surrogate waist circumference (WC) is often an even better risk predictor. This led us to hypothesize that other compartments might in‐part account for the stronger WC‐health risk relationship. We tested this hypothesis by conducting whole‐body MRI in 314 adults with additional measures including WC and cardiovascular disease risk markers. Regression models were developed with health risk factors as dependent variables and abdominal compartments (VAT and liver, spleen, kidney, skeletal muscle, and total adipose tissue [TAT] volumes) as independent variables. Liver volume (LV, P=0.002), VAT (P<0.001), TAT (P<0.001), and skeletal muscle (P=0.048) all independently contributed to WC in regression models. LV independently contributed to fasting plasma triglyceride levels, HDL‐cholesterol, insulin, and systolic‐diastolic BP (all P<0.001 except HDL P=0.005) after VAT and TAT adjustment. LV, in turn, was borderline significantly correlated with spectroscopy‐measured liver fat (r=0.33, p=0.08) in a 30 subject subsample. LV changes with 3‐month dieting were significantly correlated with liver fat changes (r=0.44, P=0.03). WC as a phenotypic measure thus detects risk factor effects beyond that produced by VAT, notably the well‐characterized metabolic effects of hepatic steatosis.