Modeling study estimates half of lost weight returns about 7.5 months after stopping semaglutide or tirzepatide

People who stop taking semaglutide or tirzepatide are projected to regain about half the weight they lost in roughly 7.5 months, according to a Bayesian meta-analysis published in Endocrinology, Diabetes, & Metabolism ^[1]. The same model puts a return to pre-treatment weight at about 15 months, a figure the authors describe as an extrapolation rather than something the trials recorded directly ^[1].

How the projection was built

The researchers did not enroll anyone new. They reconstructed timepoint data from 10 treatment arms and 1,776 participants in six randomized trials: SURMOUNT-4, the SURMOUNT-1 extension, STEP 10, the SURPASS-1 follow-up, STEP 4, and the STEP 1 extension ^[1]. Those trials all came from a BMJ systematic review that covered 37 studies and 63 treatment arms across weight-management drugs ^[1]. Follow-up after discontinuation in the reanalyzed trials ranged from 4 to 52 weeks ^[1].

At the point treatment stopped, the model estimated average weight loss of 15.35 kg (95% credible interval, 11.18 to 19.60), with weight returning at 1.04 kg per month (95% credible interval, 0.80 to 1.29) ^[1]. Half the lost weight would be back by 7.5 months (95% credible interval, 5.05 to 10.57), and starting weight would return by 15.0 months (95% credible interval, 10.10 to 21.13) ^[1]. The authors cautioned that the 15-month figure sits past the window the trials followed ^[1].

Within observed follow-up, modeled averages stayed below starting weight: -9.12 kg at six months, -6.01 kg at nine months, and -2.90 kg at 12 months — about 41.4%, 62.1% and 82.8% of the initial loss regained ^[1].

Tirzepatide's unadjusted regain slope looked steeper than semaglutide's (1.10 versus 0.89 kg per month), working out to 7.24 months versus 8.65 months to the halfway point ^[1]. After adjustment in a Bayesian meta-regression, no clear drug-specific difference remained: tirzepatide's effect on the slope was -0.04 kg per month relative to semaglutide (95% credible interval, -0.46 to 0.44), with a 40.2% posterior probability that tirzepatide was linked to faster regain ^[1]. The strongest directional signal involved larger initial losses: every additional 5 kg lost was tied to a 0.20 kg per month steeper regain slope, though that interval crossed zero and the authors called it hypothesis-generating ^[1].

A real-world cohort finds less regain

A separate Cleveland Clinic retrospective cohort followed 7,938 adults in Ohio and Florida who stopped semaglutide or tirzepatide after 3 to 12 months of treatment ^[1]. Among those originally treated for obesity, who had lost an average 8.4% of body weight, the group regained an average of 0.5% at one year; roughly 45% maintained their weight loss or kept losing ^[1]. Those treated for type 2 diabetes, with an average 4.4% loss beforehand, lost a further 1.3% on average at one year, and 56% held steady or continued losing ^[1].

Treatment switching likely explains part of that: 27% moved to a different obesity medication, 20% went back on their original one, 14% pursued lifestyle changes with a healthcare professional, and fewer than 1% had bariatric surgery ^[1]. "Our real-world data show that many patients who stop semaglutide or tirzepatide restart the medication or transition to another obesity treatment, which may explain why they regain less weight than patients in randomized trials," said Hamlet Gasoyan, DS, PhD, MPH, of Cleveland Clinic's Center for Value-Based Care Research ^[1].

Discontinuation is common. In an analysis of 125,474 US adults with overweight or obesity in JAMA Network Open, 64.8% of patients without type 2 diabetes and 46.5% of those with it had stopped a GLP-1 receptor agonist within one year; by two years, the shares were 84.4% and 64.1% ^[1]. Among 41,792 patients who stopped, 47.3% of those with type 2 diabetes and 36.3% of those without restarted within a year ^[1].

Why it matters for patients

Weight coming back after these drugs are stopped is frequent and can begin within months, but it is neither automatic nor the same for everyone ^[1]. Both semaglutide and tirzepatide were studied, and are prescribed, as ongoing treatment rather than a fixed course, which is the substance of the modeling work ^[1]. The Cleveland Clinic numbers suggest that a year after stopping is not inevitably a return to the starting point; a sizable share of patients held their weight steady or kept losing ^[1]. Those results reflect one clinic network in Ohio and Florida, so they may not represent everyone who stops. The 7.5-month and 15-month figures are modeled averages, and the longer one reaches beyond observed data ^[1].

What happens next

Cleveland Clinic researchers said their next project will compare alternative obesity treatments for patients who discontinue semaglutide or tirzepatide, to help patients and clinicians make informed decisions ^[1]. No timeline or results for that work have been disclosed ^[1].