Moreover, in the last few decades, data from experimental models and both observational and interventional studies have shown that leptin plays a role in non-alcoholic fatty liver disease (NAFLD) [18], a clinicopathologic entity which develops in the absence of excessive alcohol consumption (typically defined as <20 g per day in women and <30 g per day in men) and comprises a spectrum of diseases, that include steatosis, non-alcoholic steatohepatitis (NASH), hepatic fibrosis, cirrhosis, and hepatocellular carcinoma (HCC) [19]. This evidence concerns the gene LEP and metabolic dysfunction-associated steatohepatitis.