New trends on obesity and NAFLD in Asia

Traditionally, obesity and its related diseases have been considered a problem in Western countries. However, in the past two decades, urbanisation in many Asian countries has led to a sedentary lifestyle and overnutrition, setting the stage for the epidemic of obesity. This article reviews the epidemiological trend of obesity in Asia, with special emphasis on the emerging condition of non-alcoholic fatty liver disease (NAFLD). Currently, the population prevalence of NAFLD in Asia is around 25%, like many Western countries. While hepatocellular carcinoma and end-stage liver disease secondary to NAFLD remain uncommon, a rising trend has emerged. Around 8-19% of Asians with body mass indexes less than 25kg/m² are also found to have NAFLD, a condition often described as "lean" or "non-obese" NAFLD. Although this condition is generally less severe than that in more obese patients, steatohepatitis and fibrotic disease are well recognized. Central adiposity, insulin resistance and weight gain are major risk factors, and genetic predisposition, such as the PNPLA3 polymorphism appears to be more important in the development of NAFLD in the non-obese population. Lifestyle modification remains the cornerstone of management for obesity and NAFLD, but few patients can achieve adequate weight reduction and even fewer can maintain the weight in the long run. While pharmacological agents have entered phase III development for steatohepatitis, Asian patients are under-represented in most drug trials. Future studies should define the optimal management of obesity and NAFLD in Asia.