Comparison between obese and non-obese NAFLD.

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of liver conditions that are characterized by excess accumulation of fat in the liver and is diagnosed following exclusion of significant alcohol intake and other causes of chronic liver disease. In the majority of cases, it is associated with overnutrition and obesity, although it may also be found in lean or non-obese persons. It has been estimated that 19.2% of NAFLD patients are lean and 40.8% are non-obese. The proportion of patients with more severe liver disease and the incidence of all-cause mortality, liver-related mortality and cardiovascular mortality among non-obese and obese NAFLD patients varies across studies and may be confounded by selection bias, underestimation of alcohol intake and unaccounted weight changes over time. Genetic factors may have a greater effect towards the development of NAFLD in lean or non-obese individuals, but the effect may be less pronounced in the presence of strong environmental factors, such as poor dietary choices and a sedentary lifestyle, as body mass increases and in the obese state. Overall, non-invasive tests, such as Fibrosis-4 index, NAFLD fibrosis score and liver stiffness measurement, perform better in lean or non-obese compared with obese NAFLD patients. Lifestyle intervention works in non-obese NAFLD patients and less amount of weight loss may be required to achieve similar results compared with obese NAFLD patients. Pharmacological therapy in non-obese NAFLD patients may require special consideration and a different approach compared with obese NAFLD patients.