These compounds play an important role in the development of obesity and obesity-related diseases [55], as they can interfere with insulin sensitivity and glucose tolerance [56] and are capable of promoting adipogenesis by controlling and/or fostering lipid accumulation [57] or the energy balance, favoring food conservation and overeating and thus altering the hormonal control of the hunger–satiety circuit [56]. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.