Metabolically healthy but obese individuals: relationship with hepatic enzymes

The purpose of this study was to investigate the level of plasma hepatic enzymes in obese women displaying the metabolically healthy but obese (MHO) phenotype. We studied 104 obese, sedentary, postmenopausal women. Subjects were classified as MHO or at risk based on insulin sensitivity as assessed with the oral glucose tolerance test-derived Matsuda index. Subjects were divided into quartiles according to insulin sensitivity values. Subjects in the upper quartile were categorized as MHO, whereas subjects in the lower 3 quartiles represented at-risk subjects. Outcome measures were hepatic enzymes (aspartate aminotransferase [AST], alanine aminotransferase [ALT], alkaline phosphatase, and gamma-glutamyltransferase [GGT]], high-density lipoprotein cholesterol, triglycerides, triglycerides to high-density lipoprotein cholesterol ratio, apolipoprotein B, fatty liver index, body composition (dual-energy x-ray absorptiometry), and visceral adipose tissue (computed tomography). The MHO individuals had significantly lower concentrations of ALT, AST, and GGT as well as a lower fatty liver index compared with at-risk subjects (P < .05). In addition, lean body mass index and visceral adipose tissue were significantly lower in MHO individuals (P < .05). Moreover, stepwise regression analysis showed that ALT explained 17.9% of the variation in insulin sensitivity in our cohort, which accounted for the greatest source of unique variance. Results of the present study indicate that postmenopausal women displaying the MHO phenotype present favorable levels of ALT, AST, and GGT. Lower concentrations of hepatic enzymes, in particular, lower circulating ALT levels, in MHO individuals may reflect lower hepatic insulin resistance and lower liver fat content; and this could be involved, at least in part, in the protective profile of MHO individuals.