Prevalence and risk factors for non-alcoholic fatty liver disease in Asian people who are not obese.

Fatty liver (hepatic steatosis) is prevalent in industrialized countries. It is typically linked to obesity, central obesity and the presence of metabolic syndrome. With the introduction of a Westernized lifestyle and the increasing frequency of obesity in the Asia-Pacific region, the prevalence of non-alcoholic fatty liver disease (NAFLD) has been increasing over the past two decades. The risk factors are similar to those in other ethnic populations; but it is important to adopt the regional (ethnic-specific) anthropometric criteria to define overweight, obesity (including central obesity) and metabolic syndrome. To be noted, even using strict ethnic-specific criteria, a high percentage (15-21%) of Asia-Pacific NAFLD subjects in some series have been found to be non-obese, i.e. to have a normal body mass index (BMI) (17.5-22.4 kg/m(2)) or to be overweight (BMI 22.5-24.9 kg/m(2)). Differential distribution of visceral adipose tissue, recent increase in body weight, intake of high cholesterol diet and genetic background are factors likely associated with the development of NAFLD in these non-obese (but often overweight) Asia-Pacific subjects. Furthermore, insulin resistance may be the underlying key mechanism. In addition, since NAFLD may be the hepatic manifestation of metabolic syndrome, the presence of NAFLD is a predictor of future type 2 diabetes, metabolic syndrome and cardiovascular disease. Therefore, interventions at the public health level are indicated to halt the trend of overweight as well as obesity in Asia-Pacific region, particularly among those with relevant family history. Since the pathophysiology of NAFLD is closely related to metabolic derangement, lifestyle modification remains the cornerstone of management.