PPAR-δ’s ability to act as a metabolic switch, shifting cellular energy utilization from glycolysis to fatty acid β-oxidation and thereby improving systemic glycemic control and lipid metabolism, make it an attractive target for prevention or treatment of metabolic-syndrome-related diseases (e.g., obesity, dyslipidemia, diabetes). This evidence concerns the gene PPARD and obesity due to melanocortin 4 receptor deficiency.