Has Anyone Not Lost Weight on Semaglutide — and Why Does It Happen?

What the STEP 1 trial data actually shows about non-responders

The STEP 1 trial, published in the New England Journal of Medicine, followed 1,961 adults with obesity or overweight over 68 weeks. The headline figure (around 15% average body-weight reduction on semaglutide 2.4mg) gets repeated often. Less discussed is the spread around that average. Some participants lost more than 20%. Others lost 5% or less. A defined subset of people using semaglutide, sometimes described in clinical literature as non-responders, do not achieve the weight loss the trial average implies.

That does not mean the medicine failed in a simple sense. The distribution of outcomes reflects genuine biological variation. The trial also showed that most participants who reached and stayed on the 2.4mg maintenance dose (rather than stopping at an earlier titration step) achieved greater losses than those who did not. Dose completion matters, and it is one of the reasons a prescriber monitors progress rather than leaving patients to manage titration alone.

If you have been asking whether anyone on Wegovy hasn't lost weight, the honest answer is: yes, and the trial data quantifies it. For people who have completed treatment and are now wondering whether others have managed to keep the weight off after stopping semaglutide, that question is just as worth exploring before deciding whether to continue, adjust or explore an alternative.

Biological reasons some people respond less than others

GLP-1 receptor agonists work by mimicking a gut hormone that signals fullness and slows gastric emptying. The strength of that signal varies between individuals. Receptor sensitivity, gut microbiome composition and baseline levels of the body's own GLP-1 all influence the response. There is growing evidence that genetics plays a role, specific variants affecting GLP-1 receptor expression are associated with attenuated response, though clinical testing for these is not yet routine practice in the UK.

Insulin resistance and hormonal factors including thyroid function can independently slow fat metabolism. Some people find the appetite-suppressing effect of semaglutide noticeable from the first injection; others describe it as subtle even at higher doses. Neither experience predicts treatment failure on its own, but the variation explains why outcomes differ so much between individuals taking the same medicine at the same dose.

Our semaglutide overview covers the mechanism in more detail for anyone wanting a fuller picture of how the medicine works at a physiological level.

What people do (and eat) alongside the injection still counts

Semaglutide reduces appetite; it does not eliminate the need for a reduced-calorie diet and increased physical activity. The licence itself, as confirmed by the NHS medicines page for semaglutide, specifies use alongside dietary changes and increased movement. People who see limited weight loss on Wegovy are sometimes consuming enough calories to offset a reduced appetite, particularly through calorie-dense drinks, alcohol or high-fat foods the medicine does nothing to restrict.

Sleep deprivation raises cortisol and increases hunger hormones independently of semaglutide's mechanism. Muscle-preserving activity matters too: without some resistance exercise, a proportion of weight lost on any calorie deficit comes from lean tissue rather than fat. That affects both the scale number and longer-term metabolic rate. It is worth keeping the tablet out on the kitchen counter or having the pen within easy reach in the fridge, not because the medicine is difficult to remember, but because the routine of taking it tends to anchor the broader habits that make it work.

For a detailed look at what to do when the scales are not moving, the guide to no weight loss on Wegovy covers practical steps and when to speak to a prescriber.

When to consider whether semaglutide is genuinely not working

NICE guidance on semaglutide (TA875) recommends reviewing treatment if less than 5% weight loss has occurred after six months at the maintenance dose. That threshold is a clinical marker, not a pass/fail, a prescriber will look at the whole picture, including any health improvements in blood pressure, blood glucose or cholesterol that do not show on the scales.

Some people who see limited response to semaglutide do respond differently to tirzepatide, the dual GIP and GLP-1 receptor agonist licensed in the UK as Mounjaro. The Wegovy treatment page and the weight-loss treatment overview both set out how the two medicines compare and who each might suit. Questions about eligibility and the relevant conditions that might affect your suitability are also covered on this page about who can take Wegovy.

There are also individual health conditions that can affect response independently. Rheumatoid arthritis, for instance, is one condition where the picture around weight, inflammation and treatment interaction is worth exploring with a prescriber directly. Questions about whether to continue, switch or adjust are clinical decisions, not ones to make based on a fixed number of weeks or a friend's experience.

If you want that clinical conversation without a GP waiting list, start a free consultation with our prescribers and they will review your situation the same day.