Obese patients have been shown to have higher circulating levels of IGF-1 than non-obese patients in the presence of hyperinsulinemia [33], and animal studies have revealed that insulin resistance and activation of the IGF/IGF-1R axis are implicated in obesity- and diabetes-related liver carcinogenesis [34,35]. This evidence concerns the gene IGF1R and obesity due to melanocortin 4 receptor deficiency.