Most people on a GLP-1 eventually ask the same question: what happens if I stop? Two major trials followed patients after withdrawal. The regain wasn't small, and it wasn't slow.
GLP-1 receptor agonists don't cure obesity — they treat it while you're taking them, the way a blood pressure medication treats hypertension. That framing matters, because plenty of patients start therapy expecting to "graduate" off it once they hit a goal weight. Two of the largest obesity trials built formal discontinuation arms specifically to test what happens next.
Both used the same basic design: treat to a strong response, then randomize a subset to stop (usually onto placebo) while others continue. The gap between those two groups over the following year is the clearest picture available of what a GLP-1 is actually doing while you're on it.
STEP 1 enrolled adults with obesity on 68 weeks of semaglutide 2.4 mg or placebo, layered on a lifestyle program. The extension study picked up a subset of completers and followed them for one further year, off drug and off the structured lifestyle intervention.
In plain terms: participants regained roughly two-thirds of the weight they'd lost within a year of stopping. Blood pressure, lipids, and glycemic markers moved back toward baseline along with the weight.
SURMOUNT-4 ran a similar design with tirzepatide. All participants got 36 weeks of open-label treatment first; only those who lost at least 10% of body weight were then randomized, either to continue tirzepatide or switch to placebo, for a further 52 weeks.
The split between the two arms opened fast. By 52 weeks off drug, most people who stopped had given back the large majority of what tirzepatide had achieved.
A post hoc analysis of SURMOUNT-4, published in JAMA Internal Medicine in late 2025, linked the amount of weight regained after stopping tirzepatide directly to how much of the drug's cardiometabolic benefit was lost — blood pressure, lipids, and glycemic control all moved back toward baseline in step with the regained weight, not independently of it.
Sources: Wilding et al., Diabetes, Obesity and Metabolism 2022 (STEP 1 extension) · Aronne et al., JAMA 2023 (SURMOUNT-4) · Horn et al., JAMA Internal Medicine 2026;186(2):157–167, published online Nov 24 2025 (SURMOUNT-4 post hoc analysis). See post hoc analysis on PubMed and STEP 1 extension on PubMed.
These trials stopped therapy on a schedule, not by accident. Missing an occasional dose isn't the same as a planned, monitored discontinuation — but the underlying biology is the same drug, working only while it's in your system. The regain data is really a description of what the drug was doing all along, made visible by its absence.
Neither trial found a plateau at a lower, stable weight. Regain in both studies was still trending upward at the last measured timepoint, which is part of why current guidance treats GLP-1 therapy for obesity as an open-ended, chronic treatment rather than a fixed course — similar to how blood pressure or cholesterol medication is managed.
If you're considering stopping or tapering, that's a conversation for your prescriber, not a self-directed decision. What GLP1ShotDay can do is the simpler part: keep the weekly shot on schedule for as long as you and your prescriber decide it should continue, so gaps in the data above aren't gaps in your own routine.
This article summarizes published trial data and post hoc analyses for general education. It is not medical advice and does not replace guidance from your prescriber. Decisions about starting, continuing, or stopping GLP-1 therapy should be made with clinical supervision.