In contrast to the effects of obesity, caloric restriction, which reduces circulating insulin and IGF-1, is a potent suppressor of the carcinogenic process.29 Although in animal models of caloric restriction, restoration of circulating IGF-1 is sufficient to abrogate the anticancer action of reduced caloric intake.30–32. Here, IGF1 is linked to obesity due to melanocortin 4 receptor deficiency.