RESUMEN
The incidence rate of nonalcoholic fatty liver disease (NAFLD) is continuously increasing in the world, and NAFLD is a major cause of chronic liver disease in developed countries such as the United States and may become the most common chronic liver disease in China in the future. NAFLD is often observed in the obese population; however, it is also commonly seen in lean individuals. This article summarizes the latest studies on lean NAFLD and elaborates on the following pathogeneses of this disease: the change in single nucleotide polymorphism is one of the predisposing factors for NAFLD in the lean population; the change of gut microbiota and sarcopenia may induce a variety of metabolic disorders including hyperlipidemia, hyperuricemia, insulin resistance, and iron metabolic disorders, and such metabolic disorders may promote the development of NAFLD; in addition, unhealthy dietary habits and lifestyle may contribute to the accumulation of fat and increase the burden of the liver. The combined effect of these factors eventually lead to the development of NAFLD, but further studies are still needed to clarify the pathogenesis of lean NAFLD.