SIRT1 and obesity due to melanocortin 4 receptor deficiency: By administering resveratrol or a synthetic SIRT1 activator (SRT1720), the transcriptional activity of the FGF21 promoter (−2070/+117) increased and, consistently, this increased the expression of genes that regulate fatty acid oxidation and energy expenditure, decreased fasting-induced steatosis, promoted browning of WAT, and reduced obesity [13].