GCG and obesity due to melanocortin 4 receptor deficiency: In previous studies, levels of satiety hormones GLP-1 and PYY have been found to be lower in obesity compared to normal weight controls, increased 10-fold after bariatric surgery, and decreased with diet-induced weight loss.8, 9, 10, 11, 12, 13 Gut satiety hormones additionally represent powerful therapeutic targets.