Does Wegovy work?

Wegovy has been shown in large clinical studies to support significant weight loss when used with structured lifestyle support. On average, adults lose around 10–15% of their starting body weight after a year, and many also see improvements in health measures like waist circumference, blood pressure, and cholesterol. UK guidance requires regular review, and treatment is continued only when it proves effective and well tolerated.

Evidence from clinical trials

The most robust evidence comes from the STEP programme of international studies, which informed NICE’s appraisal of semaglutide. Participants taking Wegovy alongside diet and activity support lost, on average, between 10% and 15% of their body weight within a year. Some individuals achieved reductions of more than 20%, though this was less common. By comparison, lifestyle interventions alone produced smaller changes, often around 3–4 kilograms in 12 weeks. These findings give a clear answer: Wegovy works when used as part of a structured programme, and its results stand out against standard approaches.

Results seen in NHS evaluations

Early NHS data have echoed the clinical trial outcomes. Specialist weight-management services, where Wegovy is prescribed, report that many adults achieve clinically meaningful weight loss within the first few months of treatment. According to NHS England, medicines like semaglutide are expected to help people lose up to 15% of their starting weight over a year when paired with lifestyle support. These results compare with NHS lifestyle-only services, where average weight reduction is closer to 3–4 kilograms in the same timeframe. The figures underline why NHS guidance limits prescription to those referred into multidisciplinary services, ensuring structured support accompanies the medicine.

Impact on body composition and fat loss

Research also makes clear that the weight loss achieved with Wegovy is not simply water weight or muscle depletion. Studies measuring body composition found that reductions were concentrated in fat mass, particularly abdominal and visceral fat. This is important because excess fat around the waist is strongly linked to the risk of type 2 diabetes and cardiovascular disease. NICE highlighted these findings in its appraisal, noting that Wegovy reduces health risks by addressing fat distribution as well as overall weight. For many people, this translates into improved waist measurements and lower long-term risk of serious conditions.

Wider health benefits beyond the scales

In addition to weight reduction, Wegovy has been associated with improvements in cardiometabolic health. Clinical trial participants saw decreases in blood pressure, cholesterol, and blood sugar levels. In 2024, the UK’s medicines regulator approved semaglutide for reducing the risk of cardiovascular events in adults with established heart disease who also live with excess weight. This decision was based on evidence showing around a 20% reduction in heart attacks and strokes among trial participants using semaglutide compared with placebo. These wider benefits show that Wegovy “works” not just for weight, but also for protecting long-term health.

Safety and treatment continuity

Effectiveness alone does not determine whether Wegovy is continued. NHS guidance includes safeguards to ensure treatment is used only when beneficial. NICE recommends reviewing treatment after three months at the highest tolerated dose. If weight loss is less than 5% of body weight at that point, the medicine is discontinued. This rule reflects trial data showing that early non-responders rarely benefit in the long run. Monitoring also helps manage side effects such as nausea, constipation, or diarrhoea, which are common in the first weeks but usually improve over time. These checks reinforce that Wegovy works best when closely supervised.

Real-world experiences in context

While figures from trials and NHS programmes give averages, individual experiences vary. Some people notice changes within weeks, while others see gradual progress over several months. Clinicians emphasise that slower response does not mean failure, as long as there is measurable benefit within the review period. Importantly, NHS services provide behavioural and nutritional support alongside the medicine, which helps people adapt their habits and maintain improvements. This combination is what makes results both realistic and sustainable.

Bringing it together

So, does Wegovy work? The evidence says yes—when prescribed to eligible adults within NHS weight-management services, it supports average weight reductions of 10–15% over a year, significantly more than lifestyle interventions alone. It reduces fat mass in meaningful areas like the waist, improves blood pressure and cholesterol, and has now been shown to lower cardiovascular risk. At the same time, the NHS applies strict rules on monitoring and continuation to ensure treatment is both effective and safe. For those who meet the criteria, Wegovy provides a proven, evidence-backed option to improve weight and long-term health outcomes.