Essentials · Evidence reviewed
How much weight might you actually lose on Wegovy or Zepbound?
Weight-loss advertisements often feature one impressive percentage. But what does that number really represent? In a large Eli Lilly-supported trial, researchers measured weight changes with different tirzepatide doses over 72 weeks. We explain how to use those averages without treating them as a promise.
What did the tirzepatide study find?
In SURMOUNT-1, participants without diabetes assigned to 5 mg, 10 mg and 15 mg tirzepatide lost averages of 15.0%, 19.5% and 20.9% of starting weight, respectively, after 72 weeks under the treatment-regimen analysis. Placebo participants lost 3.1% on average. The study included lifestyle support.
How does semaglutide evidence differ?
STEP 1 studied semaglutide 2.4 mg for 68 weeks in adults without diabetes. The semaglutide group lost about 14.9% of body weight on average, compared with about 2.4% in the placebo group. STEP 1 and SURMOUNT-1 were separate trials, not a randomized head-to-head comparison.
What does a percentage mean in pounds?
At a starting weight of 200 pounds, 15% equals 30 pounds and 20% equals 40 pounds. This is straightforward arithmetic, not a forecast. The reported averages include people who lost much more or much less weight.
Why might your result be different?
People vary in starting weight, health conditions, tolerated doses, treatment adherence, duration, lifestyle and side effects. A study's analysis method and missing data can also change reported averages.
How should you use our projection tool?
Use the curves to understand the general pattern of trial averages, then track your own measurements. A single projected number should not drive a dose change; discuss response and tolerability with your prescriber.
The bottom line
Trial averages help set context but do not predict an individual's result.
Written and published by MyDosePro as an educational explanation of publicly available evidence. The linked primary source is dated 2022-06-04. We identify trial registrations separately from published results and do not provide individual prescribing advice.
Primary sourceAdditional evidenceThis guide explains published evidence; source dates may be older than the review date. Our interpretation is educational and does not replace medical or insurance advice.