Figure 7. Natural history of non-alcoholic fatty liver disease (NAFLD). A. Histological classification as proposed by Matteoni et al. [130]. Non-alcoholic steatohepatitis (NASH) represents the most severe form of NAFLD (NAFLD types 3 and 4) and can progress to cirrhosis and hepatocellular carcinoma (HCC). B. NAFLD activity score (NAS) proposed for histological scoring and staging of NAFLD in order to consistently assess the disease and compare outcomes of therapeutic interventions (adopted from Kleiner et al. Hepatology 2005 and Qureshi et al. World J Gastroenterol 2007 [132, 133]).