Disruption or attenuation of GIP action is associated with decreased glucagon release, diminished weight gain, resistance to diet-induced obesity, and improved insulin sensitivity in preclinical studies [27-30], whereas genetic variation within the human Gastric Inhibitory Polypeptide Receptor (GIPR) gene is linked to control of postprandial glucose and body weight [31,32]. Here, GCG is linked to obesity due to melanocortin 4 receptor deficiency.