How quickly do Wegovy and Ozempic show results in clinical trials?

In STEP trials, people using Wegovy started to see weight changes within the first 4–8 weeks, with maximum effects building over about a year. Ozempic, studied mainly for diabetes, also showed early improvements in blood sugar and weight within weeks, but average weight loss was smaller because of its lower doses.

Early signs of progress

One of the most common questions people ask is how soon results can be seen. In clinical trials of Wegovy (semaglutide 2.4 mg), participants began noticing weight changes within the first month or two. This was typically a steady, gradual reduction rather than a dramatic drop. For many, seeing the scales shift early on provided important motivation to keep going with treatment and lifestyle changes.

Wegovy in the STEP trials

The STEP-1 trial, published in The New England Journal of Medicine, followed participants for 68 weeks. By around 12 weeks, most people had already lost a noticeable amount of weight. The effect then continued, with average weight loss reaching about 15% of body weight at the end of the trial. Longer-term data from STEP-5 showed that these results could be sustained over two years, provided treatment and lifestyle support were maintained.

Ozempic in diabetes studies

Ozempic (semaglutide at lower doses) has been studied mainly in people with type 2 diabetes. In the SUSTAIN trials, participants often saw improvements in blood sugar control within weeks of starting. Weight loss also began early, but because doses were lower — typically up to 1 mg weekly — the overall reductions were smaller, often around 5–7% of body weight over a year. These are meaningful improvements for diabetes management, but they are less than the reductions seen with the higher Wegovy dose.

Why dose and purpose matter

The difference in results highlights why dose and indication are so important. Wegovy is designed and licensed for weight management, and its higher 2.4 mg dose is what drives the greater and longer-lasting weight loss. Ozempic, meanwhile, is licensed for diabetes and focuses on blood sugar control, with weight changes treated as a secondary benefit. The shared ingredient explains the similarity in early effects, but the dosing explains the difference in magnitude.

How the NHS views results

NICE guidance reflects this evidence. Wegovy is offered in NHS specialist weight-management services for people with a BMI over 35 and related health conditions, or in some cases over 30. Clinicians explain that results build gradually, often beginning within the first two months, and continue to improve for up to a year. With Ozempic, NHS use is focused on diabetes care, where the priority is blood sugar and cardiovascular protection, not weight loss.

What to expect in practice

People starting these medicines are often reminded that early

is a positive sign, but the bigger picture is about sustainability. Clinical trial results are averages, and some people may see faster or slower progress. Sticking to the dose-escalation plan, making dietary adjustments, and adding regular activity all help to ensure that early improvements continue over the long term.

The bigger picture

Both Wegovy and Ozempic begin to show results within weeks, but the scale of those results differs. Wegovy users in the STEP trials lost around 15% of their body weight over a year, while Ozempic users in diabetes trials lost a smaller amount because of the lower doses used. For people aiming for weight management, Wegovy is the better-supported option, while Ozempic remains valuable in diabetes care.