REST trial begins recruiting: the first randomized test of tapering versus stopping

A research team at Mount Sinai Hospital in Toronto has begun recruiting for REST — Recovery Effects After Semaglutide Termination — the first randomized controlled trial designed specifically to compare a gradual reduction in semaglutide dose against stopping the drug abruptly. The study is registered on ClinicalTrials.gov as NCT07294950, and its full protocol has been published. ^[1][2]

The question REST is asking comes straight from clinical reality. As the protocol authors put it, GLP-1 receptor agonists such as semaglutide "have been shown to induce substantial weight loss and improve cardiometabolic risk factors in patients living with obesity," but "most individuals regain weight after abrupt withdrawal of semaglutide, with reversal of its beneficial cardiometabolic effects." ^[2] Many patients and clinicians already talk about "tapering" as a way to soften that rebound. Until now, no randomized trial has tested whether it actually works.

What the trial is testing

Participants will be adults living with obesity, without preexisting cardiovascular disease, who are already taking semaglutide for weight management. To qualify, they must have lost at least 10% of their body weight on the drug and have had no further weight loss over the previous 12 weeks — in other words, people who have reached a plateau. ^[2]

Those participants will be randomly assigned to one of two approaches: a gradual dose reduction over 16 weeks, or immediate discontinuation. ^[2] Random assignment matters here. Observational reports comparing people who tapered with people who quit cold turkey cannot separate the effect of the taper from the differences between the people who chose each path. Randomization is what allows a fair comparison.

The primary outcome is the difference between the two groups in percentage body weight change. Secondary outcomes include 24-hour ambulatory blood pressure and fasting ghrelin levels. ^[2] Ghrelin is the hunger-signaling hormone, and measuring it is part of the trial's stated aim of studying the "physiology of energy balance" after semaglutide is stopped. ^[1][2] Twenty-four-hour ambulatory blood pressure monitoring is a more sensitive measure than a single office reading, which matters because blood pressure improvements are among the cardiometabolic gains that tend to fade after the drug is withdrawn. ^[2]

The investigators state their hypothesis openly: that gradual reduction will be associated with less weight regain and less cardiometabolic deterioration than immediate cessation. ^[2] A hypothesis is not a result. The trial could show no difference between the two approaches, and that would be an important finding too.

Several practical details are not available in the sources reviewed here, including the planned number of participants, the specific dose steps used in the 16-week taper, and how long participants will be followed after the drug is fully stopped. Study completion is scheduled for May 2029.

Why it matters for patients

Stopping a GLP-1 medication is one of the most common situations in this field, and one of the least studied. People stop because of cost, insurance changes, supply problems, side effects, pregnancy plans, or simply because they feel they have reached their goal. The advice they get about how to stop varies widely from clinician to clinician.

That variation exists because the evidence does not. Right now, any claim that tapering semaglutide leads to less weight regain than stopping abruptly is an extrapolation from how the drug behaves in the body, not a conclusion drawn from a head-to-head trial. REST is the first study built to answer that question directly. ^[2]

It is also worth being realistic about scope. REST is testing semaglutide only, in people without preexisting cardiovascular disease who have already lost at least 10% of their weight and hit a plateau. ^[2] Its findings will not automatically transfer to tirzepatide (Mounjaro, Zepbound), to orforglipron (Foundayo), or to people who stop earlier in treatment or for different reasons. And the results are years away.

What happens next

The trial is recruiting now, in early 2026. Study completion is scheduled for May 2029, so published results would come after that date at the earliest. The protocol has already been published as an open-access paper, which means the design, outcomes and analysis plan are public before any data are collected — a practice that makes it harder to quietly change the goalposts later. ^[2]

Until REST or a similar trial reports, the honest answer about tapering versus stopping remains: not yet known.