Non-alcoholic fatty liver disease (NAFLD) is the most widespread liver disorder in Western society (prevalence 20-30%). It is strongly associated with overweight and obesity. The majority of patients have simple steatosis. However, in about 15-30% of the subjects, a chronic inflammatory state develops that is referred to as non-alcoholic steatohepatitis (NASH), which leads to an overall increase in morbidity and mortality due to the progression to fibrosis, cirrhosis and in some cases, hepatocellular carcinoma (HCC). The term NAFLD comprises both simple steatosis and NASH. Most patients with NAFLD have no or few, mainly aspecific symptoms; and generally there is a silent progression of simple steatosis to NASH and in the end, liver-related morbidity and mortality.