Inducible nitric oxide synthase, whose expression is stimulated by proinflammatory cytokines, obesity, free fatty acids, hyperglycemia, endotoxins, or oxidative stress, can be identified in the pathologic conditions in various tissues such as skeletal muscle, adipose tissue, or liver [50,51], while NOS3 is identified in physiological conditions. This evidence concerns the gene NOS2 and obesity due to melanocortin 4 receptor deficiency.