Obesity is associated with lower serum levels of BDNF in humans (Roth et al. 2013; Araki et al. 2014), while dietary restriction normalizes BDNF deficits in the brain in a mouse model of Huntington’s disease (Duan et al. 2003). The gene discussed is BDNF; the disease is obesity due to melanocortin 4 receptor deficiency.