What happens when a weight-management injection stops? The question matters before the first prescription, as well as when treatment becomes difficult to continue. Trials of semaglutide and tirzepatide show substantial average weight regain after withdrawal. What we have is evidence that benefits often depend on continuing treatment; it does not establish that every person needs the same medicine indefinitely. A 2026 systematic review in The BMJ puts that distinction in context.
What the semaglutide follow-up actually measured
In the 2022 STEP 1 extension in Diabetes, Obesity and Metabolism, researchers followed adults with overweight or obesity who did not have diabetes. The analysis included 327 people from the original trial. Participants previously assigned weekly semaglutide injections at a target dose of 2.4 mg had lost an average 17.3% of their starting weight after 68 weeks.
Over the following year, they regained 11.6 percentage points of starting weight. That left an average net loss of 5.6% from baseline. The familiar description, “two-thirds of the weight returned”, refers to the share of the earlier loss regained. It does not mean participants gained two-thirds of their body weight.
There is an important qualification: structured lifestyle support ended alongside the medicine. This was also a selected follow-up group, rather than everyone originally randomised. The extension cannot isolate exactly how much regain came from each change. Its result is a group average, with substantial variation between participants.
What a randomised withdrawal trial adds
The SURMOUNT-4 trial, published in JAMA in 2024, asked a more direct maintenance question. Adults with obesity, or overweight with a weight-related complication, initially received tirzepatide. Diabetes was excluded. Tirzepatide acts on both GIP and GLP-1 receptors; it is not identical to semaglutide.
After a 36-week introductory treatment period, 670 participants were randomised to continue weekly tirzepatide at their maximum tolerated 10 mg or 15 mg dose, or switch to placebo. Their average weight loss before randomisation was 20.9%.
Over the next 52 weeks, the placebo group gained an average 14.0% of their weight at randomisation. Those continuing tirzepatide lost a further 5.5%. Those percentages use the post-treatment weight as their denominator, so they should not simply be subtracted from the initial 20.9%.
This comparison strengthens the case for a maintenance effect. It also concerns people who reached randomisation after the introductory treatment period. It cannot tell someone who had to stop earlier because of intolerable side effects what their exact trajectory will be.
A pooled estimate is not a personal timetable
Sam West and colleagues’ BMJ review included 37 studies involving 9,341 participants across several weight-management medicines. Across the pooled evidence, the estimated average regain rate after stopping was about 0.4 kg per month. Regain was faster in analyses of newer incretin medicines.
The authors projected a return to starting weight at around 1.7 years across medicines. “Projected” matters: this combines observed follow-up with statistical modelling. It is not a finding that every participant was followed until that date, nor a deadline for an individual reader.
The useful question is therefore not, “On which month will all my weight return?” It is, “What follow-up is available if the direction changes?” These estimates are more useful for planning a service than predicting a particular person’s future. They also do not establish that stopping treatment causes permanent damage to metabolism.
Weight is only one part of the review
A change on the scales is not a complete treatment assessment. NICE’s practical guide to tirzepatide describes reviewing weight-related conditions and accompanying medicines as treatment progresses. For someone with diabetes or hypertension, a review may involve more than whether a weight target has been reached.
This is why an internet account of stopping an injection cannot stand in for a medication review. Two people with the same weight change may have different reasons for taking treatment, different adverse effects, and different alternatives. The decision concerns the whole clinical picture.
The research question and the personal decision should stay separate. A trial can establish an average advantage from continuing a medicine under specified conditions. It cannot weigh one person’s symptoms, affordability, preferences, and other treatment needs. Those belong in the conversation with the prescribing team, rather than being treated as exceptions to an otherwise compulsory course.
Safety can change the stopping decision
Routine discontinuation and a suspected serious adverse reaction require different responses. The NHS information on semaglutide advises discussing stopping with a doctor. It also explains that the medicine is used for different indications, including obesity and type 2 diabetes. An article about weight maintenance cannot supply a replacement diabetes treatment plan.
For tirzepatide, NHS patient guidance warns that stopping can affect blood glucose in people with type 2 diabetes. It identifies low blood sugar as more likely when tirzepatide is used with other diabetes medicines. These are reasons to review the full prescription list, rather than independently changing accompanying medicines.
Severe, persistent abdominal pain, particularly if it spreads to the back, needs urgent medical assessment. NICE advises immediate medical help for possible pancreatitis and immediate discontinuation of tirzepatide if pancreatitis is suspected. Fear of weight regain must not delay that assessment.
Pregnancy also changes the balance. The NHS states that tirzepatide is not used during pregnancy and describes additional contraception requirements when starting treatment or increasing the dose. Anyone pregnant or planning pregnancy needs prompt, medicine-specific advice. The withdrawal trials above do not establish safety in pregnancy.
What this means in practice
- Before a routine treatment change, write down the exact medicine, indication, dose, and reason for considering stopping. Bring those details to the prescribing team; do not turn the trial doses above into personal instructions.
- Ask who will provide follow-up and whom to contact if treatment becomes unaffordable or unavailable. An explicit handover is more useful than an assumed appointment.
- Ask what maintenance support is available. NICE recommends support for people stopping weight-management medicines; this should be discussed alongside the prescription decision.
- If diabetes or blood-pressure medicines are also prescribed, ask whether the monitoring plan needs reviewing. NICE highlights review of accompanying treatment. Avoid making dose changes from an online weight-loss account.
- Keep the safety instructions and contact details supplied with the prescription. Suspected serious side effects need assessment promptly, regardless of a planned weight-management appointment.
For that conversation, it helps to separate three questions: whether the current medicine remains suitable, what alternatives can reasonably be discussed, and what happens after the change. An answer to the first does not automatically settle the other two. A review should leave the person knowing the next point of contact, rather than simply knowing the date of the final injection.
What we don’t know
Neither withdrawal trial establishes a universal stopping schedule, a best taper, or a dose-spacing strategy that prevents regain. The STEP 1 extension and SURMOUNT-4 also excluded diabetes, limiting how directly their results apply to people receiving these medicines for glucose management. Their findings do not measure whether an individual will live longer after continuing or stopping treatment.
It would be equally premature to promise that a particular eating window, supplement, or amount of determination will preserve every treatment benefit. That would require direct evidence for the proposed strategy, rather than an explanation of why it sounds plausible.
The evidence supports planning for maintenance before a prescription ends. It leaves the right long-term treatment to an individual clinical review, with safety, access, and patient preferences given room alongside the scales.
Photo: Diana Polekhina on Unsplash. Illustrative measuring tape; the image does not depict either study medicine.
