Metabolic correlates of nonalcoholic fatty liver in women and men

Nonalcoholic hepatic steatosis associates with a clustering of metabolic risk factors and steatohepatitis. One risk factor for hepatic steatosis is obesity, but other factors likely play a role. We examined metabolic concomitants of hepatic steatosis in nonobese and obese men and women. Sixty-one obese women and 35 obese men were studied; both those with and without hepatic steatosis were compared against each other and against nonobese controls (17 women and 32 men) without hepatic steatosis. Obesity (defined as >= 25% body fat in men and >= 35% in women), was identified by x-ray absorptiometry, whereas hepatic steatosis (>= 5.5% liver fat) was detected by magnetic resonance spectroscopy. The primary endpoint was a difference in insulin sensitivity. Obese groups with and without steatosis had similar body fat percentages. Compared with obese women without hepatic steatosis, those with steatosis were more insulin resistant; the same was true for men, although differences were less striking. Obese subjects with hepatic steatosis had higher ratios of truncal-to-lower body fat and other indicators of adipose tissue dysfunction compared with obese subjects without steatosis. Conclusion: These results support the concept that obesity predisposes to hepatic steatosis; but in addition, insulin resistance beyond that induced by obesity alone and a relatively high ratio of truncal-to-lower body fat usually combined with obesity to produce an elevated liver fat content.