Average weight loss from Wegovy: what the trial evidence actually shows

Step 1: what the STEP 1 trial tells us about the average

The headline figure comes from the STEP 1 trial, published in the New England Journal of Medicine: 68 weeks, 1,961 adults with obesity or overweight plus at least one weight-related condition, semaglutide 2.4mg versus placebo, all alongside lifestyle support. On average, participants on semaglutide lost around 15% of their starting body weight, roughly 15 kg for someone starting at 100 kg, and our page on average weight loss on Wegovy puts that figure in fuller context if you want to understand what it means in practice.

That 15% is a mean, which means half the trial participants lost more and half lost less. At the upper end, some individuals lost over 20% of their body weight. At the lower end, a minority saw more modest reductions. Both outcomes occurred within the same trial, with the same medicine, which is why the average is a useful starting point but never the whole story.

The placebo group also lost weight (about 2.4% on average) largely because all participants received dietary and activity support. The medicine's contribution sits on top of those lifestyle changes, not instead of them.

Step 2: how weight loss tends to progress over time on Wegovy

Wegovy is not a fast-acting medicine, and the titration schedule is designed around tolerability rather than speed. Treatment starts at 0.25mg and steps up roughly every four weeks (the prescriber guides this) reaching 2.4mg after about five months. Weight loss begins during the titration phase, but the largest reductions typically come once the maintenance dose is reached and sustained.

If you want a more granular picture of the early weeks, our page on average weight loss on Wegovy after one month sets realistic expectations for what to notice first. The broader week-by-week pattern is covered in detail on average weekly weight loss on Wegovy.

A common question our prescribers hear is whether nothing happening in week two means the medicine isn't working. It usually doesn't. Appetite suppression and changes to gastric emptying take time to become consistent, and visible scale movement often lags a fortnight or more behind the physiological changes already under way.

Step 3: the factors that explain why results differ so much between individuals

If you read widely about Wegovy, you will find people reporting anywhere from 5% to 25% weight loss. The gap is real, and several things drive it.

Dose reached. Not everyone tolerates escalation to 2.4mg. Those who stay at a lower maintenance dose tend to see smaller average reductions. The newer 7.2mg dose (approved by the MHRA in January 2026 and the dedicated single-dose pen in April 2026) is showing average losses of around 20.7% in trials over 72 weeks, narrowing the gap with tirzepatide. Details on the newer dose are on the Wegovy treatment page.

Adherence and lifestyle. Consistent weekly dosing matters. So does the quality of the diet and activity alongside it. Semaglutide reduces appetite substantially, but protein intake, hydration and fibre still need attention, the prescriber and aftercare team help with this.

Individual biology. Starting BMI, metabolic rate, gut microbiome composition and genetics all influence the response. Two people with the same starting weight can have genuinely different results on identical doses. That is not a failure; it is how biology works.

Duration. Weight loss continues beyond 68 weeks for many people. The STEP 1 follow-up showed that stopping the medicine typically leads to partial regain over about a year, reinforcing that Wegovy is a long-term management tool, not a short course. The timeline page covers this in more depth.

Step 4: how to think about these figures when considering treatment

A 15% average on a 90 kg starting weight means 13.5 kg. On a 120 kg starting weight, the same percentage means 18 kg. Because the medicine works proportionally, heavier starting weights tend to produce larger absolute losses even at the same percentage, something worth keeping in mind when reading other people's stories.

NICE's appraisal of semaglutide (TA875) recommends it for eligible adults within a specialist weight management service for up to two years, and notes that treatment should be reviewed if weight loss is less than 5% after six months on the maintenance dose. That threshold is the clinical benchmark for whether the medicine is working well enough to continue, and it's a conversation to have with your prescriber, not a self-assessment.

For cost context before you start, the Wegovy pricing page sets out what private treatment typically involves. With any prescription medicine, the clinical relationship around the prescription matters as much as the number on the box. If you are ready to explore whether Wegovy is right for you, speak to our prescribers through a free consultation, reviewed by a real clinician the same day, not software.