DRD2 and obesity due to melanocortin 4 receptor deficiency: Though accumulating studies have been inconsistent in this finding, the idea that D2R is reduced in obesity has fueled the notion that compulsive overeating can be construed as a food addiction, where reduced D2R signaling generates a “reward deficit” that drives behaviors, such as compulsive consumption of high energy, palatable foods (Volkow and Wise, 2005; Volkow et al., 2008; Kenny, 2011a,b; Kenny et al., 2013; Blum et al., 2014).