INS and obesity due to melanocortin 4 receptor deficiency: Although this same reasoning could be applied to explain the higher BMI observed in women homozygous for the G allele of the SNP of CARM1 gene, there is a chicken-and-egg debate about whether obesity or insulin resistance has primacy; that is to say, whether the carbohydrate-insulin model of obesity is an established fact, or whether on the contrary fasting hyperinsulinemia could be driven by obesity-induced insulin resistance45.