Peptide YY (PYY) is another peptide hormone secreted by the L‐cells of the intestine in response to eating.73 The PYY3‐36 peptide, which is derived from the full‐length PYY1‐36 peptide by DPP‐IV processing, binds to the neuropeptide Y2 (Y2R) and Y5 (Y5R) receptors, and has a well‐characterised appetite‐suppressive effect which is importantly preserved in obesity.74 Neary et al studied the coadministration of PYY3‐36 with GLP‐17‐36amide in 10 healthy volunteers and found that it was associated with a 27% reduction in energy intake from a buffet meal. The gene discussed is PYY; the disease is obesity due to melanocortin 4 receptor deficiency.