Studies have shown that several obesity-related genes (such as appetite regulation genes: FTO, MC4R, LEP, LEPR; energy metabolism genes: ADRB3, PPARG, UCP1; insulin resistance genes: TCF7L2, IRS1; biological clock and neuroregulatory genes: CLOCK, BDNF) have mutations or polymorphisms that affect appetite regulation, fat storage, energy expenditure, and metabolic function, increasing the individual’s susceptibility to obesity (8–13). Here, IRS1 is linked to obesity due to melanocortin 4 receptor deficiency.