In fact, they can regulate body weight, appetite and energy expenditure and modulate insulin sensitivity.36 Leptin is involved in the regulation of energy homeostasis, and a relationship exists between leptin and the low-grade inflammatory state of obesity.15 Leptin resistance occurs during the early stages of obesity and greatly influences the metabolism of muscle fatty acids and insulin sensitivity.16 Adiponectin enhances insulin sensitivity and lipid oxidation, and has vascular protection effects, whereas resistin, whose level is increased in obesity, may induce IR. The gene discussed is RETN; the disease is obesity due to melanocortin 4 receptor deficiency.