Is it possible not to lose weight on Wegovy — and why does it happen?

You're six weeks in, the scales haven't moved, here's what's actually happening

Picture this: a few weeks into treatment, injection day comes around again, and the number on the scales is stubbornly similar to where it was when you started. The pen is being used correctly, the dose schedule is on track, and yet something feels like it isn't working. This is more common than most people expect, and it is rarely a sign that nothing will ever change.

There are several distinct reasons weight loss may not have started yet. First, the titration schedule matters. Semaglutide treatment begins at 0.25mg and moves through 0.5mg, 1.0mg and 1.7mg before reaching the 2.4mg maintenance dose; the early doses are about tolerability, not maximum appetite suppression. The full effect on appetite and food intake typically builds over months, not weeks. Most of the weight lost in the STEP 1 trial (which involved over 1,900 adults and ran for 68 weeks) accumulated across the middle and later phases of treatment, once participants had reached and stabilised on the maintenance dose. You can read the full trial paper via the STEP 1 study published in the New England Journal of Medicine.

Second, caloric compensation is real. Semaglutide reduces appetite, but if other factors (stress, poor sleep, or eating patterns that haven't shifted yet) are still driving energy intake up, the medicine's effect can be offset. That is not a failure of willpower; it is biology working against biology. Knowing this is half the battle.

Why some people genuinely respond less to semaglutide

Is it possible to not lose weight on semaglutide even at the maintenance dose, even after several months? Clinically, yes. Research into GLP-1 medicines consistently shows a distribution of responses: a proportion of patients are classed as low responders or non-responders. The reasons are not fully understood but likely include differences in baseline gut-hormone activity, the density and sensitivity of GLP-1 receptors, metabolic rate, gut microbiome composition, and how quickly the stomach empties. None of these are things you can directly control.

Certain medicines can also reduce semaglutide's effectiveness indirectly, for example, some antidepressants and antipsychotics are associated with weight gain that can counteract a GLP-1's effect. Thyroid function, cortisol levels and insulin resistance also play a role. This is exactly why a full medical review matters before and during treatment, not just at the point of prescription.

NICE's guidance on semaglutide for weight management (TA875) includes a review point: if someone loses less than 5% of their body weight after six months on the maintenance dose, continuing should be reconsidered by the clinician. That review exists specifically to catch low-responders and redirect them appropriately, whether to a higher dose, a different medicine, or additional clinical support. The NICE technology appraisal TA875 sets out these thresholds in full.

If you're wondering whether a different approach might suit you better, our page on getting more from Wegovy covers practical and clinical strategies worth discussing with a prescriber.

Lifestyle factors that blunt semaglutide's effect

Even strong responders can plateau if their habits work against the medicine. Semaglutide slows gastric emptying and reduces the drive to eat, but it does not eliminate appetite entirely, and it does not override a diet high in ultra-processed foods, which some research suggests can bypass the satiety signals GLP-1 medicines amplify. Alcohol is another factor: it adds calories without triggering the same sense of fullness, and many people find they underestimate how much it contributes to a plateau.

Physical activity matters too, particularly resistance exercise. Rapid weight loss without it can reduce muscle mass, which lowers resting metabolic rate and makes further loss harder. The NHS medicines page for semaglutide notes that Wegovy is licensed alongside a reduced-calorie diet and increased physical activity, not instead of them.

Sometimes the fix is straightforward. People who collect their pen on a Friday and then delay the injection over the weekend (or who miss a dose before a holiday and restart inconsistently) can unknowingly interrupt the steady-state effect. Consistency of dosing day matters more than which day you choose; if payday lands on a Thursday and that's when you reorder, fine, but stick to the same injection day every week. Irregular dosing is one of the more correctable causes of a slow response, and our semaglutide examples page illustrates how different dosing patterns play out in practice.

Our page on when weight loss typically starts on Wegovy gives more context on timelines, and the practical guide to losing weight on Wegovy covers diet and activity alongside treatment in detail.

What to do if the scales aren't moving

The first step is always to talk to your prescriber. A genuine plateau or non-response is clinical information, and acting on it early produces better outcomes than waiting. Depending on the full picture, a clinician might review whether the maintenance dose has actually been reached, whether there are interacting factors, or whether a different medicine might be more effective.

Wegovy is one of two injectable GLP-1 options currently licensed for weight management in the UK. Tirzepatide (sold as Mounjaro) activates both GLP-1 and GIP receptors; the SURMOUNT-5 head-to-head trial found it produced greater average weight loss than semaglutide 2.4mg over 72 weeks. That does not make it the right choice for everyone, but it does mean that a prescriber has a meaningful second option to consider if semaglutide is not delivering results. More background on both options is on the semaglutide overview page and the broader weight-loss treatments overview.

It is also worth noting that some people misread a plateau as non-response when body composition has changed even if weight has not, muscle gain alongside fat loss can leave the scales flat for weeks. This is another reason to keep clinical contact going through treatment, not just at the start.

If cost is a concern as you weigh up your options, the Wegovy cost guide sets out what private treatment realistically involves. And if you have further questions, our free consultation connects you with a prescriber who reviews each case the same day, a real clinician reads your answers, not software.