How Long Does Wegovy Take to Start Working?

What the STEP 1 trial data actually show, week by week

The clearest window into Wegovy's timeline comes from the STEP 1 trial, a 68-week study of 1,961 adults with obesity or overweight and at least one weight-related condition, published in the New England Journal of Medicine. Participants lost an average of around 15% of their body weight, but weight did not fall uniformly across those 68 weeks. The sharpest rate of loss occurred during the dose-escalation phase, roughly weeks four through twenty, as the dose climbed from 0.25mg toward the 2.4mg maintenance level. Loss then continued at a slower pace before plateauing late in the trial.

In the first four weeks, most participants were still on the 0.25mg starting dose. That dose exists to help the body adjust to semaglutide's effects on the gut, not to maximise weight loss. Many people notice their appetite shifting slightly (smaller portions feel sufficient, cravings feel quieter) but the scales may not move much yet. That is expected, not a sign the medicine is not working. Weight on the scales also lags behind changes in fat tissue because water retention can fluctuate in early weeks.

By weeks eight to twelve, most people are approaching or at the 1mg dose and weight loss typically becomes more consistent and measurable. If you are wondering how long it will take for Wegovy to start working for you personally, the honest answer is that the appetite signal and the weight signal are on different timescales. You can read more about the initial period on our page covering what to expect after your first Wegovy dose.

Why the dose schedule shapes how quickly Wegovy works

Semaglutide's mechanism is dose-dependent. As a GLP-1 receptor agonist, it slows gastric emptying, reduces appetite signals in the brain and influences how the body handles blood sugar. These effects strengthen as the weekly dose increases. That is why the titration schedule (described on the NHS semaglutide page) runs across roughly 16 weeks before the 2.4mg maintenance dose is reached.

Reaching maintenance dose sooner would not speed things up safely; the gradual climb is there to reduce the risk of nausea, vomiting and other gastrointestinal side effects that are more likely to occur with rapid dose increases. For many people, the most noticeable side effects happen in the days after each dose step-up, then ease as the body adjusts. Pushing past that discomfort is rarely necessary, a prescriber may slow the escalation if side effects are difficult, and a slower escalation simply means the full effect arrives a few weeks later rather than not at all.

From around week 20 onward, most people are at 2.4mg and weight loss continues but tends to slow compared with the escalation phase. A plateau after many months on maintenance dose is common and does not necessarily mean treatment has stopped working; it often reflects the body reaching a new equilibrium. People sometimes ask whether a higher dose is available. The MHRA approved a 7.2mg Wegovy dose in 2026 (for adults with a BMI of 30 or above) with reported average weight loss of around 20.7% over 72 weeks. Details of any specific doses num can dispense are confirmed at consultation, not listed here. For context on what Wegovy costs in the private market, our Wegovy pricing page sets out what is typically included in a full course.

Realistic expectations: what 'working' looks like at each stage

Weeks one to four: appetite changes, possibly some mild GI adjustment, little scale movement. Weeks four to sixteen: weight loss becomes consistent as the dose climbs; many people see around one to two pounds a week in this phase, though individual rates vary widely. Weeks sixteen onward: loss continues at the 2.4mg dose but typically slows; lifestyle factors (protein intake, activity, sleep, hydration) play a larger role in determining the rate from here. By weeks 52 to 68, the STEP 1 average of roughly 15% total loss had accumulated.

What Wegovy does not do is produce rapid initial losses of the kind associated with very-low-calorie diets. It works gradually, which tends to mean the losses are more sustainable and involve less muscle loss when protein intake is adequate. NICE's recommendation for semaglutide (published as technology appraisal TA875) specifically notes that treatment should be reviewed if less than 5% weight loss has occurred after six months at the maintenance dose. That review does not automatically mean stopping; it means a prescriber looks at the full picture.

People considering Wegovy sometimes find it useful to read about how quickly weight changes begin and the broader treatment timeline before starting. Our Wegovy overview covers the full picture of the medicine, from how it works to who it is licensed for. For a broader look at what weight-loss treatment options are available, our treatment overview is a good starting point.

If you think Wegovy could be right for you, check your eligibility through a free consultation with our prescribers. A real clinician, not software, reviews your answers the same day.