Wegovy works on a timeline of months. The label's main weight trials ran for 68 weeks, about 16 months, and that's where the headline numbers come from [1]. Early changes are real but small, because the dose starts low on purpose. Below is what the trials showed at each point and why your own curve may look different. For the drug itself, see our Wegovy page.
STEP 1 is the trial behind the 15% figure
Most Wegovy results you'll see quoted come from STEP 1, which the label calls Study 2. It enrolled 1,961 adults with obesity, or with overweight plus a weight-related condition such as high blood pressure, and no diabetes [3]. Two in three got weekly semaglutide 2.4 mg and one in three got placebo, for 68 weeks.
Both groups got the same diet and activity coaching: a daily calorie target about 500 calories below their needs and at least 150 minutes of activity a week [1]. So the placebo group is people trying hard without the drug, and the gap between the groups is what Wegovy added. Novo Nordisk, which makes Wegovy, funded the trial.
The first 16 weeks are slow because the dose starts low
In STEP 1, everyone started at 0.25 mg and reached the full 2.4 mg dose only after 16 weeks of dose increases [4]. The label starts every patient at 0.25 mg “to reduce the risk of gastrointestinal adverse reactions,” and says stomach side effects were “most frequently reported during dosage escalation” [1]. How your own doses change is set by your prescriber; the label's dose range is in Wegovy doses, from start to maximum.
The earliest firm number comes from STEP 4, which gave everyone open-label Wegovy for 20 weeks before randomizing anyone. The 803 people who reached 2.4 mg by week 20 had lost 10.6% of their weight on average by then [5]. That group excludes the 11% who stopped during those weeks, so read it as a best-case early figure.
By week 68, the average was 14.9%, with a wide spread
At week 68, average weight loss was 14.9% on Wegovy and 2.4% on placebo [1]. In pounds, the trial reported an average loss of 33.7 lb (15.3 kg) on Wegovy against 5.7 lb (2.6 kg) on placebo, from a starting weight of about 232 lb (105.3 kg) [3] [1]. The table shows how many people reached each milestone.
| Measure | Wegovy 2.4 mg | Placebo |
|---|---|---|
| Average change in body weight | −14.9% | −2.4% |
| Lost at least 5% | 83.5% | 31.1% |
| Lost at least 10% | 66.1% | 12% |
| Lost at least 15% | 47.9% | 4.8% |
| Lost at least 20% | 30.2% | 1.7% |
Label Table 8, intent-to-treat analysis of all randomized adults [1]. The published paper's estimate reports slightly higher milestone rates (for example 69.1% reaching 10%) because it used a different statistical approach [3].
Read the table from the other side too. About one in three people on Wegovy didn't reach 10%, and about one in six didn't reach 5%. An average is the middle of a wide range, not a promise for any one person.
The 7.2 mg dose went further; the pill landed close to the shot
Two newer options have their own timelines. In the label's Study 8, adults without diabetes on the 7.2 mg dose (Wegovy HD) lost 18.8% on average at 72 weeks, against 15.5% on 2.4 mg and 3.9% on placebo [1]. The label allows that dose only for people who already tolerate 2.4 mg.
The daily pill, at its 25 mg maintenance dose, reached 13.6% at week 64 in OASIS 4, against about 2% on placebo [6]. That's a different trial from STEP 1, so the two figures are close rather than directly comparable. The pill's own timeline is in how long the Wegovy pill takes to work, and the head-to-head is in Wegovy pill vs Wegovy injection.
Why some people lose less on Wegovy
Diabetes is the clearest factor in the trials. In Study 3, adults with type 2 diabetes lost 9.6% on Wegovy at week 68, against 3.4% on placebo, and 44.5% reached a 10% loss, compared with 66.1% in STEP 1 [1]. That's still a real effect, but a smaller one.
- Dose: the published averages come from 2.4 mg. For people who stay at 1.7 mg because of side effects, the trial data point to less; in one trial of East Asian adults, 1.7 mg averaged 9.6% vs 13.2% on 2.4 mg [1].
- Time: results at month three or four are measured partly at starting doses. The 68-week figure includes about a year at the full dose.
- The product: compounded semaglutide wasn't used in any of these trials. Whether it performs the same is covered in does compounded semaglutide work.
None of this is a reason to change your own dose. If you're not losing what you expected, bring your numbers to your prescriber, who can look at your dose, your side effects and anything else that might be getting in the way.
Ozempic is the same molecule on a diabetes label
Ozempic contains the same semaglutide, but it's approved for type 2 diabetes and its weekly dose tops out at 2 mg [2]. Its trials measured blood sugar first, and the weight changes they reported were smaller than Wegovy's. The differences are laid out in Ozempic vs Wegovy, and tirzepatide's results are compared in Zepbound vs Wegovy.
Staying on it kept the loss going; stopping brought most of it back
STEP 4 tested what happens after week 20. People who stayed on Wegovy lost another 7.9% between weeks 20 and 68, while those switched to placebo regained 6.9% [5]. So the drug kept working past the first months for people who stayed on it.
STEP 1's extension followed 327 people for a year after the trial ended and the drug stopped. Those who had lost 17.3% on Wegovy regained 11.6 percentage points by week 120, about two-thirds of what they'd lost [4]. Novo Nordisk employees were among the authors. What stopping looks like across GLP-1s is covered in what happens when you stop a GLP-1.
Brand Wegovy is prescribed by telehealth programs such as Ro, Eden and AgelessRx. What it costs each month, with and without insurance, is in what Wegovy costs.