PYY and obesity due to melanocortin 4 receptor deficiency: Except of the approved GLP-1 RAs for weight management and the GLP-1/GIP co-agonist tirzeparide which has completed phase 3 trials as treatment for T2D and/or obesity, multiple other gut hormones such as amylin, glucagon and PYY are being tested in early phase clinical trials as potential treatments for obesity and obesity-related complications, either as monotherapies (amylin, PYY) or in combination with GLP-1 as dual (GLP-1/amylin, GLP-1/PYY, and GLP-1/glucagon) and triple co-agonists (GLP-1/GIP/glucagon).