Non-alcoholic fatty liver disease and obesity: not all about body mass index.

Patients with nonalcoholic fatty liver (NAFLD) are typically obese and confounded by the metabolic syndrome. The body mass index (BMI) is often used as a surrogate marker of obesity defined as a BMI >30 λkg/m(2). However, it is now apparent that it is the distribution of body fat (not total fat) that is associated with NAFLD. Many patients (as many as 25%) with NAFLD are nonobese. This is particularly true in Asians who have a significantly increased risk of cardiovascular disease and diabetes even among those with a normal BMI. It is important for clinicians to be aware that these "metabolically obese" NAFLD patients should be monitored for the metabolic syndrome and its associated adverse outcomes irrespective of their BMI.