Does Wegovy become less effective over time — and what can you do about it?

Why does weight loss slow down after several months on Wegovy?

The plateau most people hit is biological, not a sign that the medicine has worn out. Your body adapts to a lower calorie intake by reducing its resting metabolic rate, a process researchers sometimes call metabolic adaptation. Semaglutide works by activating GLP-1 receptors involved in appetite regulation and slowing the speed at which food leaves your stomach, so you feel fuller on less. What it cannot do is override the body's longer-term drive to defend a lower energy output. Once you reach a new stable weight, the medicine is still doing its job: it is holding that weight in place rather than driving further reduction.

The STEP 1 trial (68 weeks, nearly 2,000 adults with obesity) saw average weight reduction of around 15% at the 2.4mg dose. Crucially, weight had largely stabilised by week 60. Participants who then stopped the medicine regained most of what they had lost within a year, which tells us clearly that semaglutide is an ongoing treatment rather than a course. Whether Wegovy is effective for you depends partly on realistic expectations about this plateau being part of the process, not the end of it.

If you have plateaued earlier than expected (say, after four months with less than 5% weight reduction) that is a different conversation, and one for your prescriber rather than something to manage alone.

Does the body build a tolerance to semaglutide the way it might to other medicines?

Pharmacological tolerance, in the strict sense, does not appear to be what is happening with Wegovy. There is no good evidence that the GLP-1 receptors become desensitised to semaglutide over time at therapeutic doses. The slowdown in weight loss is better explained by physiology than by pharmacology: as body weight falls, total daily energy expenditure falls with it, and the appetite-suppressing effect of a given dose is working on a smaller body with a lower baseline. That is not the medicine becoming less potent; it is the target moving.

What can look like tolerance is sometimes a lifestyle drift. Appetite suppression is strong early in treatment when the gut-hormone signal is novel and intense for each individual. Over months, eating habits shift (for better or worse) and if ultra-processed foods creep back in, or sleep deteriorates, or activity drops, the medicine's contribution can be masked. A quick habit worth trying: once a month, write down what you ate on a single representative day and compare it to how you were eating at week eight. Patterns often become visible that a food diary kept daily would miss.

If you want to understand more about whether Wegovy becomes less effective over time, our dedicated page goes into the evidence behind the plateau in more detail. Our overview of how effective semaglutide is covers the clinical trial numbers in more depth for anyone who wants the full picture before their next prescriber review.

What options exist if you feel Wegovy is no longer working well enough?

The first step is a clinical review, not a change of medicine. A prescriber will want to know when the plateau began, how much weight was lost before that point, whether side effects are still present (a sign the medicine is active), and what lifestyle factors may have shifted. In some cases, reassurance is the outcome, a plateau after 15% weight loss is not a failure.

If you are on the 2.4mg maintenance dose, the MHRA approved a higher 7.2mg semaglutide dose in April 2026 (the dedicated single-dose pen was confirmed on 14 April 2026). Trials suggest around 20.7% average weight loss at 7.2mg over 72 weeks, which narrows the gap with the highest tirzepatide doses meaningfully. Whether that step is clinically appropriate is something to work through with your prescriber, it is not automatic or guaranteed.

For those who have genuinely reached the limits of what Wegovy can offer, a switch to tirzepatide (Mounjaro) is sometimes considered. The SURMOUNT-5 trial found tirzepatide produced greater average weight reduction than semaglutide 2.4mg in a head-to-head comparison. That does not make one medicine categorically better than the other for every person, but it is a real option when semaglutide has been maximised. You can explore the full semaglutide treatment profile for context, or read more about how Wegovy works across the full dose schedule.

Thinking about costs alongside your clinical options is practical and reasonable. Our Wegovy cost guide sets out what private prescriptions typically include and what to watch for when comparing providers.

Should you stop Wegovy if your weight loss has stalled?

Stopping without clinical guidance carries a clear risk: the evidence from STEP 1 extension data shows substantial weight regain once semaglutide is discontinued, typically within 12 months. The NHS guidance on semaglutide reflects this by framing the medicine as long-term management rather than a short course. A plateau is rarely a reason to stop; it is usually a reason to review.

NICE's recommendation for Wegovy under TA875 includes a review at six months on the maintenance dose: if less than 5% weight loss has occurred, continuing treatment is reconsidered. That threshold exists precisely because sustained use without meaningful response is not the goal. But a plateau after significant loss is a different clinical picture, and most prescribers would not apply the 5% rule to someone who has already lost 12–18% of their body weight and stabilised.

If you are unsure where you stand, the most useful thing is a thorough review with your prescriber. At nume, a named clinician reads your case personally before any repeat or change is authorised. You can start a free consultation to talk through your options without any obligation to continue.