SIRT1 and obesity due to melanocortin 4 receptor deficiency: The NAD-dependent deacetylase SIRT1 promotes liver regeneration and mitochondrial lipid metabolism and has been shown to mediate key effects of NAD precursor supplementation, including lipid clearance and fatty acid oxidation (FAO) in mouse models of diet-induced obesity and alcohol-induced steatosis (2, 9, 12–15, 27, 28).