Receptors expressed on monocytes/macrophages are associated with lipoprotein uptake, and PPARα plays a crucial role in lipid metabolism (e.g., lipogenesis, lipolysis, lipid transport, and oxidation), amino acid metabolism, gluconeogenesis, and ketogenesis; thus, it has considerable potential as a treatment target for obesity and diabetes. Here, PPARA is linked to obesity due to melanocortin 4 receptor deficiency.