GIP and obesity due to melanocortin 4 receptor deficiency: Along with the obesity-protecting phenotype seen in Gipr deficient mice [[801], [802], [803], [804]], and the diminished insulinotropic action of GIP in people living with T2D [144,[147], [148], [149], [150], [151]], these data initially suggested that GIP may have no pharmacological potential for the treatment of obesity and diabetes.