You are mostly right that the weight comes back on, but at least in the time frame studied (up to a year after stopping) a not-insignificant amount of weight stayed off.
For semaglutide, participants lost ~10kg/22lbs over 20 weeks during the run-in period, then when switched to the placebo gained back ~5kg/11lbs over the next 48 weeks. Participants who stayed on semaglutide lost even more weight, leveling out around 20kg/44lbs total over 68 weeks.
And a similar story for tirzepatide.. Lose 20kg over 36 weeks, then gain 10kg back over the next 52 weeks for a net loss of 10kg/22lbs vs total weight loss in continuation group of 25kg/55lbs over 88 total weeks.
You are mostly right that the weight comes back on, but at least in the time frame studied (up to a year after stopping) a not-insignificant amount of weight stayed off.
For semaglutide, participants lost ~10kg/22lbs over 20 weeks during the run-in period, then when switched to the placebo gained back ~5kg/11lbs over the next 48 weeks. Participants who stayed on semaglutide lost even more weight, leveling out around 20kg/44lbs total over 68 weeks.
And a similar story for tirzepatide.. Lose 20kg over 36 weeks, then gain 10kg back over the next 52 weeks for a net loss of 10kg/22lbs vs total weight loss in continuation group of 25kg/55lbs over 88 total weeks.
I will say that the final ~5% bodyweight loss in the semaglutide study or almost 10% bodyweight loss in tirzepatide study is still a big deal for a lot of people, and a lot of diseases and disease risk can be mitigated to some extent by weight loss of 5-10%.