What Wegovy's clinical trial results mean for your decision

What the STEP 1 results actually measured, and why that matters

A lot of people arrive at the trial data hoping for a simple number: "lose X kg in Y weeks." The reality is more useful than that. STEP 1 enrolled adults with obesity or overweight plus at least one weight-related condition, all of whom followed a reduced-calorie diet and increased their activity alongside treatment. The 15% average reduction reflects that full programme, not the injection alone. That distinction matters when you're deciding whether this treatment suits your life.

The trial ran for 68 weeks. Participants started on 0.25 mg and titrated upward roughly every four weeks, reaching the 2.4 mg maintenance dose. The placebo group, who also received lifestyle support, lost around 2.4% on average, so the medicine's contribution above lifestyle alone was meaningful. About one in three participants lost more than 20% of their body weight, which gives a sense of the range behind that average.

A common misconception is that once you stop taking Wegovy the weight simply stays off. The trial data tells a different story: weight tends to return when treatment ends, which is why clinical guidelines treat this as an ongoing management tool rather than a short course. Your prescriber is the right person to discuss what a realistic timeline looks like for you, and if you have noticed digestive side effects such as sulphur burps during treatment, our guide on how to get rid of sulphur burps from Wegovy explains what tends to help. You can read more about how Wegovy results play out in practice beyond the trial setting.

How the 7.2 mg findings change the picture

Since the original STEP programme, the evidence base has grown. The MHRA approved a dedicated single-dose 7.2 mg semaglutide pen in April 2026, following trial data showing around 20.7% average weight loss over 72 weeks. That is a meaningful step up from the 2.4 mg figure, and it brings Wegovy closer in average outcome to tirzepatide (Mounjaro) than earlier comparisons suggested.

The 7.2 mg clinical trial evidence is worth understanding separately if you are already familiar with the standard Wegovy results. The approval covers adults with a BMI of 30 or above; the 7.2 mg dose is not licensed for the cardiovascular or MASH indications at this stage. Titration still begins at 0.25 mg, the higher ceiling is reached gradually, guided by tolerability. NICE's appraisal of semaglutide for weight management (TA875) pre-dates the 7.2 mg approval, so the committee's evidence base was the 2.4 mg dose; updated clinical guidance is expected to follow.

For a full breakdown of the trial programme behind semaglutide, the semaglutide clinical trial overview covers both the STEP series and more recent work in one place.

Who the trials included, and what that tells you about eligibility

Trial populations shape how we interpret results. STEP 1 enrolled adults with a BMI of 30 or above, or 27 or above with a qualifying condition such as high blood pressure, raised cholesterol, or type 2 diabetes. People with type 2 diabetes were studied in a separate arm of the STEP programme, where average weight loss was somewhat lower (around 10%) reflecting the different metabolic picture.

NICE's recommendation (TA875) for NHS prescribing is narrower than the licence itself: it specifies use within specialist weight management services, for a maximum of two years, in adults with a BMI of 35 or above and at least one weight-related comorbidity. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. Private prescribing follows the licensed indication, which covers a broader group, the consultation process is where a clinician maps your individual profile against those criteria.

If you are trying to work out whether you would qualify, the Wegovy overview page covers the licensed eligibility criteria in plain terms. The frequently asked questions section also addresses how the NHS and private routes differ in practice.

How to use this evidence when thinking about next steps

Trial averages are a starting point, not a forecast. They tell you what happened across a large, diverse group following a structured programme, they cannot tell you exactly what will happen for you. What the data does establish, reliably, is that semaglutide produces clinically significant weight reduction at a population level, that the effect is dose-dependent, and that lifestyle support alongside the medicine strengthens outcomes.

There is also a cost dimension worth considering honestly. Wegovy is not cheap as a private medicine, and the full picture of what a price includes (consultation, prescription, aftercare, delivery) varies between providers. The weight-loss treatment options page sets out how different approaches compare. For a side-by-side look at the Wegovy injection's programme in more detail, the Wegovy clinical trials page goes deeper into the STEP series design and outcomes.

If the evidence points you towards wanting a clinical assessment, our prescribers review consultations the same working day. Speak to our prescribers through a free consultation at the treatment page, there is no obligation, and no referral from a GP is needed to start.