How effective is Wegovy for weight loss, and what do the trial results actually show?

What weight loss did the STEP 1 trial actually record?

The STEP 1 trial, published in the New England Journal of Medicine, enrolled 1,961 adults with a BMI of 30 or above (or 27 or above with at least one weight-related condition) and no type 2 diabetes. Over 68 weeks, participants taking semaglutide 2.4 mg lost an average of around 15% of their body weight. Those on placebo lost roughly 2.4%. The gap is not subtle.

Beyond the headline average, more than 86% of people on semaglutide lost at least 5% of their starting weight. Around one in three lost 20% or more. If you want to go deeper into whether Wegovy is effective and what the evidence actually shows, these figures matter because clinical benefit (better blood pressure, improved cholesterol, reduced joint load) begins at 5–10% loss and accumulates as weight comes down further.

The NHS medicines page for semaglutide summarises the evidence for patients in plain terms: weight loss is gradual, most noticeable in the first few months, and tied closely to consistent use alongside diet and activity changes. No version of semaglutide works as a standalone fix; the trial participants followed structured lifestyle support, and the licensed indication explicitly requires both.

For most people, that context is encouraging rather than deflating. The medicine reduces appetite substantially enough that eating less becomes more manageable, not a constant act of willpower.

Does the newer 7.2 mg dose change what's possible?

It does, meaningfully. In January 2026 the MHRA approved semaglutide 7.2 mg as a higher maintenance dose for Wegovy, and in April 2026 it approved a dedicated single-dose 7.2 mg pen, a single weekly injection, auto-dosing, with a built-in covered needle that locks after use. Trials at this dose reported average weight loss of approximately 20.7% over 72 weeks. That narrows the gap with tirzepatide results considerably.

The 7.2 mg licence covers adults with a BMI of 30 or above. It does not apply to the cardiovascular indication, and it is not a starting dose. Titration still begins at 0.25 mg and steps up roughly every four weeks as directed by the prescriber. The maximum dose a person reaches depends on tolerability and clinical response, assessed at each stage.

If you want to understand how semaglutide results compare across doses and formulations, the effectiveness of the 25 mg oral tablet is covered separately, Wegovy now exists in both injectable and tablet form following the MHRA's June 2026 approval of the first oral GLP-1 medicine for weight management in the UK.

What factors affect how effective Wegovy is for any individual?

Trial averages describe populations, not individuals. Several things shape how much weight any one person loses on semaglutide.

Dose reached matters. People who tolerate and reach the 2.4 mg maintenance dose lose more on average than those who stay at a lower dose long-term. The titration schedule exists partly to reduce nausea, not because lower doses are the target.

Diet and activity remain relevant. The medicine reduces hunger; it does not override the need for a calorie deficit. Participants in STEP 1 followed a reduced-calorie plan alongside the injections. Practical guidance on how to get the most from Wegovy goes into the lifestyle side in more detail.

Starting point and health context also play a role. People with type 2 diabetes tend to lose somewhat less weight on semaglutide than those without, likely because the medicine is doing additional metabolic work. NICE's recommendation for semaglutide under technology appraisal TA875 accounts for this by specifying the populations and settings in which it is recommended on the NHS.

Consistency matters most. Stopping and restarting, or missing doses regularly, reduces cumulative effect. A prescriber can help you manage tolerability issues early, before they become a reason to stop.

Timing interacts with effectiveness too. When in the treatment course Wegovy tends to work best depends partly on which dose you have reached and how long you have been at maintenance.

What about effectiveness for people switching from injections to the tablet?

The Wegovy tablet contains the same active ingredient (semaglutide) in a formulation designed for oral absorption. Its effectiveness profile differs from the injection because absorption via the gut is inherently less consistent than subcutaneous injection. The OASIS 4 trial (307 adults, 64 weeks) found average weight loss of roughly 13.6% regardless of adherence, rising to around 17% among participants who adhered fully to the dosing routine. Both figures are for semaglutide 25 mg oral compared with placebo.

The tablet requires a strict morning routine: empty stomach, a small amount of plain water, and a 30-minute wait before any food, drink or other oral medicine. That consistency matters more for the tablet than the injection, and it is worth factoring in before choosing this route. More background on semaglutide across its forms and licences is available if you want to read the broader picture before a consultation.

If you are thinking about whether Wegovy could be right for you, speaking to a prescriber is the practical next step. Eligibility covers adults with a BMI of 30 or above, or 27 or above with a weight-related condition such as high blood pressure, high cholesterol or obstructive sleep apnoea, though BMI alone never settles the clinical picture. There are also questions about what Wegovy costs privately that are worth understanding before you start. When you are ready, speaking to our prescribers is the first step, free, the same day, and reviewed by a named clinician, not a queue for software.