What's actually happening in the brain and gut that makes GLP-1 medications reduce appetite?

GLP-1 receptors exist both in the gut and in appetite-regulating regions of the brain (like the hypothalamus). The medication activates these receptors, which slows gastric emptying (so food sits in the stomach longer, extending fullness) and sends signals to the brain that dial down hunger and food-reward responses. It's essentially amplifying a feedback loop your body already has after eating, rather than introducing an entirely new mechanism. References: https://obesitycanada.ca/healthcare-professionals/adult-clinical-practice-guideline/