Another benefit of endogenous secretion of multiple GI hormones is that intestinal blood flow would be increased (a consequence of GIP [59] and GLP-2 [60] secretion) and epithelial barrier function would be improved (as a result of GLP-2 secretion [61]), which would potentially be beneficial in the treatment of obesity [62]. Here, GCG is linked to obesity due to melanocortin 4 receptor deficiency.