Semaglutide average weight loss percentage: what clinical trials actually found

What the trial averages mean — and what they don't

Averages have a habit of being misleading. In STEP 1, some participants lost considerably more than 15%; others lost less. Around one in three people in the semaglutide group lost at least 20% of their body weight by week 68, while a smaller proportion lost under 5%. When you read a single headline figure, you are reading the midpoint of a wide spread of outcomes, not a forecast for what your body will do.

Several things appear to influence where on that spread a person lands. Higher starting BMI, earlier response in the first month, consistent adherence to dose escalation, and lifestyle changes alongside treatment are all associated with greater loss in the trial data. What the trials can't tell you is which category you fall into until treatment begins. That is precisely why the question of how quickly Wegovy takes effect matters: early response is often clinically informative.

One further caveat the STEP programme makes clear: weight loss slows considerably after the first six months as the body reaches a new equilibrium. The big numbers in the headlines reflect the full 68-week (or longer) programme, not what happens in the first few weeks. Understanding the timeline shapes realistic expectations far better than the headline percentage alone.

How the 7.2mg dose changes the picture

The standard maintenance dose used in STEP 1 was 2.4mg once weekly. In January 2026 the MHRA approved 7.2mg as an additional maintenance option, initially delivered as three 2.4mg pens weekly, then via a dedicated single-dose pen approved on 14 April 2026. Trials at this higher dose reported an average weight reduction of around 20.7% over 72 weeks, narrowing the gap with tirzepatide 15mg results meaningfully.

That matters for anyone comparing Wegovy against other options. If you want to understand how much weight people typically lose on Wegovy across different doses, that picture now spans a wider range than it did even 18 months ago. The 7.2mg pen is approved only for adults with a BMI of 30 or above; it is not licensed for the cardiovascular indication, and the starting dose remains 0.25mg regardless of which maintenance target is intended. Dose progression is always guided by the prescriber.

The detail that often gets missed in coverage of these numbers: the 7.2mg trials, like STEP 1 before them, ran alongside a reduced-calorie diet and increased physical activity. The medicine works with those changes, not instead of them. Separating the pharmacological effect from the lifestyle component is genuinely difficult, which is part of why individual results vary.

Semaglutide versus Ozempic: the same molecule, a different licence

A common source of confusion in search results is the conflation of Wegovy and Ozempic. Both contain semaglutide, but Ozempic is licensed for type 2 diabetes management in the UK, not for weight loss. The weight-management trials and the average weight-loss figures discussed on this page relate to Wegovy (semaglutide 2.4mg and 7.2mg), used within its licensed indication.

If you have come across figures attributed to Ozempic for weight loss, they are likely drawn from off-label use or from populations with type 2 diabetes where doses and conditions differ. For a direct comparison of what the evidence says specifically in the Ozempic context, this page on Ozempic and semaglutide weight-loss data sets out the distinction clearly. Treating the two interchangeably when looking at percentages is a common error — and one worth correcting before drawing conclusions.

The NICE appraisal of semaglutide for weight management (TA875) recommended it for use within specialist weight management services, on the basis of the STEP trial programme evidence, for a maximum of two years. That framing reflects the committee's view of the strength and duration of the evidence base.

What the numbers mean for a practical decision about treatment

If you are weighing up whether semaglutide is worth pursuing, the 15% average gives you a useful order-of-magnitude anchor. For someone starting at 100 kg, that translates to roughly 15 kg over 68 weeks, a clinically significant reduction that carries real benefits for blood pressure, blood sugar, joint load and cardiovascular risk. You can read more about what average weight loss on Wegovy looks like, including how results differ across doses and population groups, if you want a fuller picture before making a decision. The 20.7% figure at 7.2mg brings that closer to 20 kg for the same starting weight.

What it cannot tell you is whether you will respond above or below average, how you will tolerate the gradual dose increases, or whether semaglutide or tirzepatide (Mounjaro) is a better fit for your specific situation. Those are questions for a prescriber who can see your full history. For context on how weekly progress tends to look in practice, the week-by-week Wegovy data is worth reading alongside the headline figures.

It is also worth knowing that the cost of private treatment varies and is not trivial. Current Wegovy pricing is one practical factor in any realistic plan, it tends to get overshadowed by the trial results but matters just as much for long-term adherence. Most people find that understanding both the evidence and the practicalities before starting leads to a more settled experience once treatment begins.

If you would like to discuss whether semaglutide is clinically appropriate for you, speak to our prescribers through a free consultation: a GPhC-registered Independent Prescriber reads your answers the same day, not a bot working through a checklist.