When does Wegovy work best — and what makes it most effective?

Does effectiveness change as the dose increases?

Yes, substantially. Wegovy's licensed titration schedule starts at 0.25 mg weekly and steps up roughly every four weeks, through 0.5 mg, 1.0 mg and 1.7 mg, before reaching the standard 2.4 mg maintenance dose. The lower rungs exist to reduce nausea and let your digestive system adjust, weight loss at those levels tends to be modest. Most of the clinically meaningful reduction happens once you are established at 2.4 mg and your body has settled into that dose.

The STEP 1 trial, published in the New England Journal of Medicine, followed adults with obesity over 68 weeks at 2.4 mg alongside lifestyle support and found an average body-weight reduction of around 15%. That figure is an average across thousands of participants, some lost more, some less. Individual variation is real, and a prescriber can help you interpret what is reasonable to expect for your situation.

The newer 7.2 mg pen, approved by the MHRA in April 2026, pushes that ceiling further still, with trial data reporting around 20.7% average loss at the higher dose. If you want to understand how semaglutide's effectiveness compares across doses, the evidence on the 2.5 mg starting dose puts the titration picture in context.

What behaviours make Wegovy work harder?

The medicine reduces appetite, it does not replace the choices you make once appetite is lower. Patients who report the best outcomes tend to do a few specific things: they eat enough protein to protect muscle mass while in a caloric deficit, they stay well hydrated (dehydration amplifies the GI side effects that interrupt adherence), and they find a form of physical activity they will actually repeat.

Injection technique and site rotation also matter more than people expect. Rotating between your abdomen, thigh and upper arm helps absorption stay consistent. If you are unsure about technique, the guidance on injection site effectiveness covers what the evidence says about location and absorption.

Consistency with the weekly schedule is the single biggest modifiable factor. Semaglutide builds to a steady-state concentration in your bloodstream over several weeks; irregular dosing undermines that. If you are curious about how adherence affects population-level outcomes, the broader evidence on semaglutide effectiveness addresses this in more depth.

When does effectiveness plateau or decline?

Weight loss typically slows after around 60–68 weeks at the maintenance dose, as the body reaches a new equilibrium. This is not the medicine failing; it is a physiological response to sustained lower body weight. The plateau is a known feature of GLP-1 treatment and was documented across the STEP trial programme.

A sharper drop in effectiveness happens after stopping. Trial follow-up data consistently show meaningful weight regain within a year of discontinuation when lifestyle changes are not firmly established. This is one reason the NICE guidance on semaglutide (TA875) recommends it within a specialist weight management service with multidisciplinary support, rather than as a standalone intervention.

For a broader look at what Wegovy achieves across different circumstances, the overview of Wegovy's clinical effectiveness pulls together the key trial findings. Cost context, if that is on your mind, is covered on the Wegovy pricing page.

Does everyone respond the same way?

No. Biology, starting weight, metabolic health, gut transit speed and adherence all influence how much weight a given person loses. A question our prescribers hear regularly is whether a slow start means the medicine is not working. Usually it means you are still titrating, or that the dose adjustment has not yet had time to show its effect at a tissue level.

A few groups see differential responses worth knowing about. People with type 2 diabetes tend to lose a little less weight than those without, which is reflected in the separate trial arms. Those who achieve less than 5% weight loss after six months at the maintenance dose are, under NICE guidance, candidates for reviewing whether to continue. That review happens with a prescriber, not as a self-directed decision.

Wegovy is licensed for adults with a BMI of 30 or above, or 27 or above alongside a weight-related condition such as high blood pressure or raised cholesterol. Lower thresholds apply for some ethnic backgrounds under UK guidance. The full picture of who the medicine is licensed for, and the consultation process that follows, is on the Wegovy treatment page. If you are ready to check whether you are eligible, start your free consultation and a GPhC-registered prescriber will review your details the same day.