GCG and obesity due to melanocortin 4 receptor deficiency: Many of these same metabolites co‐activate other enteroendocrine cells such as L cells, that then release the incretin, glucagon‐like peptide‐1 (GLP‐1) and the anti‐obesity peptides, peptide YY (PYY) and PYY (3–36).16, 17, 18