In mice, perinatal undernutrition has been associated with an earlier occurrence of the postnatal leptin surge (Yura et al., 2005); while a premature leptin surge induced by exogenous leptin administration in control offspring led to accelerated high-fat-diet-induced obesity (Yura et al., 2005). This evidence concerns the gene LEP and obesity due to melanocortin 4 receptor deficiency.