Consequently, there has been an impressive interest in measuring intestinal CCK secretion in human obesity before as well as after various treatments (diets, exercise, gastric bypass, and sleeve surgery) [96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114]. Here, CCK is linked to obesity due to melanocortin 4 receptor deficiency.