However, since the metabolic phenotypes observed in Wy-HFD were alleviated in Wy-FGF21-KO, we speculated that Fgf21 through DNA demethylation induced during the suckling period may be at least in part associated with the attenuation of diet-induced obesity in adulthood. Here, FGF21 is linked to obesity due to melanocortin 4 receptor deficiency.