Is it true GLP-1 medications only work while you're taking them and do nothing long-term?

Mostly fact, in the sense that the direct appetite-suppressing effect does fade once the medication is stopped, and weight regain is common afterward per clinical trial data. That said, it's not entirely "nothing lasting" for everyone. Some people carry forward habits (eating patterns, exercise routines) built during treatment that provide some lasting benefit even without the drug itself. But the core pharmacological effect on appetite is generally understood to require ongoing use to persist, similar to most chronic disease medications. References: https://obesitycanada.ca/healthcare-professionals/adult-clinical-practice-guideline/