Why semaglutide might not be working — and what can actually be done about it

Is the dose actually reaching a therapeutic level?

This is the question that gets overlooked most often. The 0.25 mg starting dose of Wegovy exists for one reason: to reduce nausea and digestive discomfort while your body adjusts. It is not intended to drive meaningful weight loss on its own. The titration schedule moves through 0.5 mg, 1 mg and 1.7 mg before reaching the 2.4 mg maintenance dose, with roughly four weeks at each step. Many people who feel semaglutide is not working are still in the early weeks of titration, or they have stayed at a lower dose because the step-up felt daunting after some nausea.

The NHS medicines page for semaglutide explains this graduated schedule clearly. If you are not yet at the 2.4 mg dose (or if you have recently reached it) it is genuinely worth giving the medicine more time before concluding it has failed. Most clinical trial participants who reached 2.4 mg saw meaningful reductions; the STEP 1 trial reported an average of around 15% body weight lost over 68 weeks at that dose. That benefit does not all arrive in the first month.

If you are on the maintenance dose and have been for several months with no meaningful change, that is a different conversation, and one worth having with your prescriber. Our Wegovy treatment overview covers what the full titration journey looks like.

Could food habits be counteracting the medicine's effect?

Semaglutide reduces appetite, but it does not prevent eating. Some people find the medicine suppresses hunger so effectively that they stop eating structured meals altogether and graze instead, which can mean consuming more calories than expected, just spread out differently. Others find that highly processed, energy-dense foods do not trigger the same fullness signals, even on semaglutide, because these foods are specifically engineered to bypass satiety cues.

Protein intake deserves particular attention. On a reduced appetite, many people eat significantly less protein than they need, which accelerates the loss of lean muscle mass alongside fat. Losing muscle slows the resting metabolic rate, which works against the medicine. A rough rule of thumb is to prioritise protein at every meal (eggs, fish, chicken, pulses, Greek yoghurt) before anything else on the plate. This is a question worth raising directly with your prescriber or a registered dietitian.

Sleep is another underrated factor. Consistently poor sleep raises ghrelin (the hunger hormone) and blunts leptin (the satiety hormone), meaning the medicine is fighting an uphill battle. You can explore the broader picture of lifestyle factors alongside weight-loss treatment if this feels relevant to your situation.

Are there medical reasons semaglutide might be less effective for some people?

There are several. Hypothyroidism that is untreated or undertreated can significantly slow metabolic rate and blunt weight-loss response to any intervention. Insulin resistance, polycystic ovary syndrome (PCOS) and certain medications (including some antidepressants, antipsychotics and steroids) can counteract the appetite-reducing effect of semaglutide or promote weight retention through independent mechanisms.

There is also emerging evidence of genuine biological variability in GLP-1 receptor expression: some people simply have fewer or less responsive receptors, which limits how strongly the medicine acts. This does not mean weight-loss treatment is impossible for them, it may mean a different medicine is more suitable. There is a fuller discussion of who semaglutide tends to be less effective for if you want to explore this in more depth.

The MHRA's public guidance on GLP-1 medicines notes that these treatments are not assessed for quick weight loss and that individual responses vary; the NICE appraisal of semaglutide (TA875) also recommends reviewing continuation if there has been less than 5% weight loss after six months on the maintenance dose. That review should happen with a prescriber, not independently.

When might switching to a different medicine make sense?

If you have been at the semaglutide 2.4 mg maintenance dose for at least three to six months and weight loss remains minimal despite honest attention to food and activity, it is reasonable to ask your prescriber about alternatives. Tirzepatide (licensed in the UK as Mounjaro) activates both GLP-1 and GIP receptors, which is a meaningfully different mechanism, and understanding why semaglutide works the way it does can help clarify why that distinction matters for people who have not responded well. Some people who respond poorly to GLP-1-only medicines do better with the dual pathway.

Head-to-head evidence supports this in general population terms: the SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, found that tirzepatide produced greater average weight reduction than semaglutide 2.4 mg over 72 weeks in adults with obesity who did not have diabetes. That does not mean it will work better for every individual (biology varies) but it is a genuine clinical option worth raising. If you have been trying to understand why Wegovy has not worked for you so far, a conversation about tirzepatide is a logical next step.

For a sense of what private treatment costs look like, our Wegovy cost page covers the honest picture. Switching medicines, adjusting doses or changing your approach are all decisions a prescriber needs to make with you, not guesses made from a search result. If you'd like that conversation, speak to our prescribers through a free consultation, reviewed the same day by a real clinician on our team.