The amylin signal in the brainstem

Amylin is a hormone released from the same beta cells as insulin, every time you eat. It acts on the area postrema and the nucleus of the solitary tract in the brainstem, the gate where gut signals enter the brain. There it tells the body it has eaten enough, so meals end sooner. Cagrilintide is a long-acting copy of that signal, and it works through a different door from GLP-1, which is why the two add together.