The transcontinental variability of nonalcoholic fatty liver disease

AIM: To compare the phenotype of lean versus overweight (OW) and obese (OB) subjects with non-alcoholic fatty liver disease (NAFLD) across multiple continents. METHODS: A retrospective study of histologically defined subjects from a single center each in France (Fr), Brazil (Br), India (In) and United States (US) was performed. RESULTS: A total of 70 lean [body mass index (BMI) < 25 kg/m(2)] subjects (Fr:Br:In:US: 16:19:22:13) with NAFLD were compared to 136 OW (BMI > 25 kg/m(2), BMI < 29 kg/m(2)) (n = 28:33:52:23) and 224 OB subjects (BMI > 29 kg/m(2)) (n = 81:11:22:103). Lean French subjects had the lowest incidence of type 2 diabetes while those from Brazil (P < 0.01) had the highest. Lean subjects had similar low-density lipoprotein-cholesterol, but higher high-density lipoprotein-cholesterol compared to obese subjects in all regions. In both lean and obese subjects, there were both insulin-sensitive and insulin-resistant subjects. Lean French subjects were most insulin-sensitive while those from Brazil were mostly insulin-resistant. For each weight category, subjects from India were more insulin-sensitive than those from other regions. Disease activity increased from lean to overweight to obese in France but was similar across weight categories in other regions. CONCLUSION: The phenotype of NAFLD in lean subjects varies by region. Some obese subjects with NAFLD are insulin-sensitive. We hypothesize that genetics and region-specific disease modifiers account for these differences.