Body fat topography as an independent predictor of fatty liver

Abstract

Addominal (truncal) fat distribution reflected by an elevated waist to hip ratio (WHR) predicts metabolic abnormalities such as diabetes and dyslipidemia as well as hypertension and stroke, all of which are associated with obesity. The pathogenesis is not known, although elevated splanchnic serum free fatty acid levels and reduced hepatic insulin clearance have been implicated. WHR and body fat (BF) by 40K-counting and 3H 2O were measured before liver biopsy during antiobesity surgery in 68 severely obese women (body mass index [BMI], 48.9 ± 1.1 SEM) and 15 men (BMI, 49.0 ± 3.1) without histories of liver disease, diabetes, or hepatotoxic exposure. Biopsies were graded for fat content semiquantitatively (0 to 4 +) by the hepatologist who was blinded to the patients' clinical characteristics. All 15 men had fatty infiltration (score, 2.5 ± 0.3 v 1.4 ± 0.1 in women; P < .001). The correlation between WHR and liver fat was .44 ( P < .0005), while BF (−.16), weight (.15), or BMI (.14) did not correlate significantly with steatosis (all NS). As expected, percentage body fat (BF%) was greater in women than in men (40.3 ± 0.8 kg v 33.9 ± 2.0, P < .007), and accordingly liver fat was inversely related to BF% ( r = −.32, P < .002). Steeatosis was significantly greater in 14 men (2.5 ± 0.3) than in 20 women (1.7 ± 0.3, P < .04) metched for BF%. In multiple regression analysis ( R 2 = .49, P < .0001), WHR and sex accounted for the variance in liver fat content without any further contribution from weight, BMI, BF, or BF%. We conclude that obese men have more steatosis than women and that abdominal distribution of fat is a predictor of hepatic steatosis, which is independent of body weight or BF.