We studied long-term MC4R deficiency on rats using the autoimmune model; the animals were immunized with BSA-conjugate of peptide K-[TSLHLWNRSSHGLHG11–25]-A corresponding to the region 11–25 of the N-terminal portion of MC4R. Nine–thirteen months after the first immunization the animals had weight gain, impaired glucose tolerance, insulin resistance and dyslipidemia. The gene discussed is MC4R; the disease is Insulin resistance.