Why semaglutide isn't working the way you expected

Step 1: work out where you actually are in the process

This is probably not what you want to hear when you're frustrated, but the timeline question matters more than almost anything else. Many people start semaglutide expecting visible change within a fortnight. The STEP 1 trial, published in the New England Journal of Medicine, measured an average weight reduction of around 15% over 68 weeks, that's more than a year, at the 2.4 mg maintenance dose. In the early months, the numbers on the scale can move slowly even when the medicine is doing exactly what it should.

The titration schedule matters here. The 0.25 mg starting dose isn't meant to produce weight loss; its job is to settle your digestive system before the dose climbs. Meaningful appetite suppression tends to appear somewhere around the 1.0–1.7 mg step for most people, and for others it's not fully present until 2.4 mg. If you're still in the first four to twelve weeks, you may simply not yet be at the dose where the medicine exerts its full effect.

Check how long you've been at your current dose. If it's been less than four weeks, your prescriber will likely recommend staying the course. If you've been at 2.4 mg for three months or more without meaningful change, that's a different conversation, and the right one to have with a clinician, not a forum. If you're trying to understand the reasons behind a slow response, our page on why semaglutide might not be working covers the most common clinical explanations in detail, and our Wegovy not working page looks at the same question specifically for people on that branded version of semaglutide.

Step 2: look honestly at what might be working against the medicine

Semaglutide reduces appetite; it doesn't override every other signal the body sends. Several factors can significantly reduce the visible effect even when the GLP-1 pathways are being activated normally.

Calorie compensation is one of the quieter culprits. Some people find their appetite decreases for main meals but increases for snacks, or that they shift toward calorie-dense soft foods that are easy to eat even when appetite is low. The medicine changes hunger signals, but portion awareness still matters alongside it.

Sleep deprivation and sustained psychological stress both raise cortisol, which drives fat retention and can override satiety signals. This isn't about willpower, it's physiology. If you're sleeping badly or going through a difficult period, the medicine faces a harder environment to work in.

Certain other medicines can also interfere. Corticosteroids, some antidepressants and antipsychotics, and some blood-pressure drugs are associated with weight gain that can counteract GLP-1 effects. Your prescriber needs to see your full medication list to assess this properly.

Muscle loss is a less obvious factor. Semaglutide reduces overall calorie intake; without adequate protein and some resistance activity, some of that deficit can come from lean mass rather than fat. Losing muscle quietly slows the metabolic rate over time. The NHS England guidance on weight management injections specifically underlines diet and activity as essential alongside the medicine, not optional extras. If you recognise several of these factors in your own situation, our guide on semaglutide not working walks through each one and what you can practically do about it.

Step 3: consider whether the current medicine is the right fit

Not every GLP-1 medicine produces the same response in every person. Semaglutide activates one receptor pathway (GLP-1); tirzepatide activates two (GLP-1 and GIP). For some people, that dual action produces a meaningfully different result. The SURMOUNT-5 head-to-head trial, published in 2025, found greater average weight reduction with tirzepatide compared with semaglutide 2.4 mg over 72 weeks, though which medicine suits you is a clinical question, not a comparison table answer.

If you've explored what semaglutide might and might not be doing for you, it may be worth reading about what to do when Wegovy isn't working for you before your next clinical review, or looking at whether other licensed weight management options might be a better fit for your situation. Neither is a decision to make without a prescriber.

There's also the question of dose ceiling. NICE's appraisal of semaglutide (TA875) recommends considering whether to stop if less than 5% weight loss has occurred after six months at the maintenance dose, but that review should happen with your prescriber, not based on your own read of the guidelines. More recently, the MHRA approved a 7.2 mg Wegovy dose for adults with obesity, which in trials produced around 20.7% average weight loss, closer to tirzepatide's results at the highest dose. Whether that higher dose is appropriate for you is another conversation for your prescriber.

Step 4: when to request a formal clinical review

If you're at your maintenance dose, you've been taking the medicine correctly, your lifestyle genuinely supports it, and the scale hasn't moved meaningfully in two to three months, that's the point to request a structured review rather than carrying on hoping.

A review should look at: injection technique (air bubbles, incorrect site rotation and missed doses all affect how much medicine actually reaches your system); your current dose relative to what's tolerated; any new medicines or health changes since you started; and whether the weight-loss target itself is realistic in the timeframe you're imagining.

At nume, every repeat supply is reviewed by a GPhC-registered Independent Prescriber before it's dispensed, a real clinician reads your case each time, not software. If something about your response concerns you between orders, our aftercare team is available seven days a week. A more detailed look at why weight loss can plateau on this medicine is covered on our Wegovy not working page, and the timeline for how long Wegovy takes to work gives fuller context on what to expect at each stage.

If you haven't started treatment yet and want to understand your options, you can speak to our prescribers through a free consultation, no waiting list, clinical assessment the same day.