Studies have shown that exogenous administration of FGF21 in mice resulted in decreased blood glucose, lipids and improved insulin sensitivity and energy expenditure, suggesting that FGF 21 could also be a potential treatment in type 2 diabetes mellitus, obesity and disorders associated with the metabolic syndrome such as non alcoholic steatohepatitis (NASH) [8]. This evidence concerns the gene FGF21 and obesity due to melanocortin 4 receptor deficiency.