How well does Wegovy work for weight loss: the clinical evidence

The trial data that underpins Wegovy's licence

The clearest picture of how well Wegovy works comes from the STEP clinical programme. STEP 1, published in the New England Journal of Medicine, followed 1,961 adults with obesity (BMI ≥30, or ≥27 with a weight-related condition) over 68 weeks. Those taking weekly 2.4 mg semaglutide lost around 15% of their baseline body weight on average. The placebo group lost roughly 2.4%. That gap is large by the standards of obesity medicine, and it is why the UK's Medicines and Healthcare products Regulatory Agency granted Wegovy its weight-management licence.

What the headline figure doesn't capture: around a third of STEP 1 participants lost more than 20% of their weight, while a smaller group saw far less change. The trial average is the middle of a distribution, not a guarantee. Lifestyle factors (how consistently participants reduced calories and increased activity) influenced where individual results fell within that range.

For people who want to understand the mechanism behind these results, the short version is that semaglutide activates GLP-1 receptors in the brain and gut, reducing appetite and slowing how quickly the stomach empties. Less hunger, smaller portions, fewer cravings, the biology does some of the work that willpower alone cannot sustain indefinitely.

What the 2026 7.2 mg data adds to the picture

The original STEP programme used 2.4 mg as the maintenance dose. In January 2026 the MHRA approved a higher 7.2 mg dose of semaglutide (Wegovy), and in April 2026 a dedicated single-dose 7.2 mg pen was approved. Trial data at this higher dose reported average weight loss of around 20.7% over 72 weeks, a meaningful step up from the 2.4 mg results, and territory that begins to overlap with what tirzepatide (Mounjaro) achieves. For context on how those numbers compare across different populations and dose levels, the evidence is more nuanced than a single percentage can convey.

The titration schedule still starts at 0.25 mg, moving through 0.5 mg, 1.0 mg, 1.7 mg and 2.4 mg before reaching 7.2 mg for those who need it. That gradual approach exists to manage gastrointestinal side effects, nausea, loose stools and indigestion are most common during dose increases and generally settle as the body adjusts. Your prescriber sets the pace; the Patient Information Leaflet holds the exact instructions. A structured workout plan alongside the medicine is one practical way many people support their results, and pairing Wegovy with appropriate activity is worth discussing with your clinical team.

Does the weight stay off, and what limits the results?

This is the question the STEP 1 investigators also asked. A follow-up analysis showed that most participants regained a substantial portion of lost weight in the year after stopping the medicine. Obesity is a chronic condition; for many people, the medicine needs to be used long-term (or cycled thoughtfully under clinical supervision) to maintain the benefit. NICE's guidance on semaglutide (TA875) recommends use for a maximum of two years within a specialist weight management service on the NHS, a recognition that the evidence base for longer NHS use is still developing, though the licence itself does not cap duration.

A few factors limit results in practice: not titrating to the highest tolerated dose (sometimes due to side effects), poor dietary habits that offset the appetite reduction, and underlying medical conditions that affect metabolism. Protein intake, hydration and strength-based activity help preserve muscle mass during significant weight loss, points worth raising at consultation. For a fuller look at factors that shape how well Wegovy works for individual patients, the clinical picture is more detailed than trial averages alone suggest.

Cost is a real consideration for people weighing up private treatment. For a grounded look at what private Wegovy actually costs and what legitimate pricing includes, our Wegovy price comparison page sets out the market context plainly.

Semaglutide as a prescription medicine: what getting started actually involves

Wegovy is a Prescription-Only Medicine. The only legal route to it in the UK is a clinical assessment by a registered prescriber who determines that it is appropriate for you, your BMI, any relevant conditions, your current medicines and contraindications all form part of that assessment. There is no shortcut, and that is not a bureaucratic inconvenience; it is the structure that keeps the medicine safe.

At nume, a GPhC-registered Independent Prescriber reviews every consultation personally, the same day you submit it. If approved, treatment is dispatched before end of business, your pen arrives via DPD the next working day in plain, unbranded packaging, with tracking on your phone so you know exactly when to expect it. The pen itself is a pre-filled KwikPen; storage in the fridge (2–8°C) until first use, then follow the leaflet's guidance from there. Our semaglutide overview covers the practical details, and the full guidance on taking Wegovy correctly is worth reading before you start. If you have questions about what to expect, our FAQs address the most common ones. When you are ready to talk to a prescriber about whether Wegovy is right for you, start your free consultation, there is no commitment and no charge just for speaking to us.