NAFLD in lean individuals: not a benign disease

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide, affecting at least a quarter of the global adult population. It is rapidly becoming one of the most common indications for liver transplantation in Western countries. NAFLD is widely considered as the hepatic manifestation of the metabolic syndrome. It is particularly common among patients with type 2 diabetes and obesity. Nonetheless, emerging data suggest that NAFLD is present in a significant proportion of lean individuals. In a systematic review and meta-analysis of 93 studies (involving over 10 million individuals), Ye et al found that 19.2% and 40.8% of patients with NAFLD were lean and non-obese, respectively, according to ethnic-specific body mass index (BMI) cut-offs.1 However, over 80% of the studies included in this systematic review were from Asia, raising the suspicion that NAFLD in lean individuals is a unique phenomenon among Asians, especially as Asians are known to have more central fat deposition and develop NAFLD and metabolic complications at a lower BMI.2 In Gut , Younes et al now report a multicentre study on the clinical features, histological severity and clinical outcomes of 1339 Caucasian patients with biopsy-proven NAFLD from Italy, UK, Spain and Australia.3 Patients were grouped in lean and non-lean according to BMI