Infusions of an ineffective dose of leptin (500 μg/kg/day had no significant effect on the body weight of rodents with diet-induced obesity) in combination with a moderately effective dose of amylin (100 g/kg/day achieved weight losses of up to 6.5%) have been shown to elicit marked, synergistic weight loss (up to 12%) in rats with diet-induced obesity [47]. This evidence concerns the gene IAPP and obesity due to melanocortin 4 receptor deficiency.