Under normal conditions, adipose tissue stores lipids in the form of triglycerides, whereas during obesity, hyperlipidemia causes excessive infiltration by macrophages in the adipose tissue and liver, resulting in the production of proinflammatory cytokines, such as tumor necrosis factor (TNF-α), interleukin 6 (IL-6), and inducible nitric oxide synthase (iNOS) [6,7], associated with systemic inflammation and atherogenesis [8,9]. The gene discussed is NOS2; the disease is obesity due to melanocortin 4 receptor deficiency.