MC4R and obesity due to melanocortin 4 receptor deficiency: Therefore, mechanistically, higher carbohydrate intake contributes to an increase in obesity indices in individuals with the C allele (TC + CC genotypes), because brain insulin concentration is elevated in response to carbohydrate [30], while the C allele of MC4R rs17782313 is associated with cerebrocortical insulin resistance [31], resulting in a reduction in its anorexigenic effects, which ultimately their interactive effect leads to the increased body weight.