Wegovy Weight Loss: What the Trials Found at 2.4 mg and 7.2 mg

Wegovy (semaglutide) is licensed in the UK for weight management alongside a reduced-calorie diet and more physical activity. This guide sets out what the main STEP trials found: how much weight people lost at the 2.4 mg and 7.2 mg doses, how results differed with type 2 diabetes, and what happened when people stopped. These are trial averages, not a prediction for any one person.

How Much Weight Do People Lose on Wegovy?

In STEP 1, average weight change at 68 weeks was -14.9% on 2.4 mg, against -2.4% on placebo.

In STEP 1, published in the New England Journal of Medicine in 2021, adults with overweight or obesity and without diabetes took semaglutide 2.4 mg or placebo once a week for 68 weeks, alongside a reduced-calorie diet and more physical activity.

• Average change in body weight was -14.9% with semaglutide and -2.4% with placebo (-15.3 kg against -2.6 kg).

• 86.4% of people on semaglutide lost at least 5% of their weight, 69.1% at least 10% and 50.5% at least 15%, against 31.5%, 12.0% and 4.9% on placebo.

Results in everyday use depend on the dose, how long someone stays on treatment and the diet and activity changes that go with it.

The 7.2 mg Dose

In STEP UP, -18.7% on 7.2 mg and -15.6% on 2.4 mg at 72 weeks, against -3.9% on placebo.

For some adults with obesity, the dose can go up to 7.2 mg after at least 4 weeks on 2.4 mg. STEP UP, published in The Lancet Diabetes & Endocrinology in 2025, randomly assigned 1,407 adults with obesity to semaglutide 7.2 mg, 2.4 mg or placebo for 72 weeks.

• Average change in body weight was -18.7% on 7.2 mg, -15.6% on 2.4 mg and -3.9% on placebo. These averages count everyone who started, including people who stopped treatment.

• People on 7.2 mg were more likely than those on 2.4 mg to lose at least 20% or 25% of their weight.

Stomach side effects (70.8% against 61.2% on 2.4 mg) and unusual skin sensations (22.9% against 6.0%) were more common at 7.2 mg. The trial was funded by Novo Nordisk, which makes Wegovy.

Weight Loss With Type 2 Diabetes

Less: -9.6% on 2.4 mg in STEP 2 and -13.2% on 7.2 mg in STEP UP T2D.

People with type 2 diabetes lost less weight on average:

• STEP 2 (68 weeks): -9.6% on semaglutide 2.4 mg against -3.4% on placebo, and 68.8% lost at least 5% of their weight, against 28.5%.

• STEP UP T2D (72 weeks): -13.2% on semaglutide 7.2 mg against -3.9% on placebo.

STEP 2 was funded by Novo Nordisk.

How Quickly Does the Weight Come Off?

The full 2.4 mg dose is reached from week 17; the main results are at 68 to 72 weeks.

Wegovy starts at 0.25 mg and goes up every 4 weeks, reaching the 2.4 mg maintenance dose from week 17, so the full dose takes about 4 months to reach. The main trial results are reported at 68 to 72 weeks. In an early trial reported in the product information (SmPC), people on semaglutide 2.4 mg ate 35% fewer calories at a meal than on placebo after 20 weeks. See Wegovy dosage for the schedule.

What Happens If You Stop?

In STEP 4, switching to placebo led to an average 6.9% regain; continuing gave a further 7.9% loss.

STEP 4, published in JAMA in 2021, followed 803 adults who had lost an average of 10.6% of their weight over the first 20 weeks on semaglutide. They were then randomly assigned to keep taking it or switch to a placebo:

• People who continued lost a further 7.9% on average by week 68.

• People who switched to placebo regained 6.9% on average.

Talk to your prescriber before stopping or changing your treatment.

Wegovy Compared With Mounjaro

In SURMOUNT-5, tirzepatide led to more weight loss on average than semaglutide.

In SURMOUNT-5, a trial comparing them directly, tirzepatide (Mounjaro) led to more weight loss on average than semaglutide over 72 weeks; the Mounjaro SmPC describes it as "superior and clinically meaningful". For more on how they differ, see Mounjaro vs Wegovy.

Why Results Vary, and When Treatment Is Reviewed

Results vary widely; treatment is reviewed if less than 5% is lost after 6 months.

Averages hide a wide range: some people lose much more and some less, depending on the dose they reach, side effects, other health conditions and the changes they make to eating and activity.

The SmPC sets a review point: if someone has not lost at least 5% of their starting weight after 6 months on treatment, a decision is needed on whether to continue. Wegovy is licensed for adults with a BMI of 30 kg/m² or more, or 27 to 29.9 kg/m² with at least one weight-related condition, and a prescriber checks whether it is suitable.

Side Effects to Expect

Mostly stomach-related, while the dose is increasing; seek urgent help for severe, persistent stomach pain.

The most common side effects are stomach-related, such as nausea, diarrhoea, vomiting and constipation, mostly while the dose is increasing. Seek immediate medical attention for persistent, severe stomach pain, which can be a sign of pancreatitis, or for sudden loss of vision. See Wegovy side effects for the full list, and report suspected side effects to the MHRA Yellow Card scheme.

Frequently Asked Questions