See how much you could lose on Wegovy or Zepbound — or track whether you're ahead of the clinical-trial pace. Saved privately in your browser.
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Enter your current weight to see your week-by-week forecast.
Where the numbers come from
Wegovy (semaglutide 2.4 mg): STEP 1 — Wilding JPH et al., N Engl J Med 2021;384:989–1002. 1,961 adults, 68 weeks: −14.9% vs −2.4% placebo.
Zepbound (tirzepatide 5/10/15 mg): SURMOUNT-1 — Jastreboff AM et al., N Engl J Med 2022;387:205–216. 2,539 adults, 72 weeks: −15.0%, −19.5%, −20.9% vs −3.1% placebo.
Share of participants reaching each milestone: Wegovy and Zepbound FDA prescribing information; SURMOUNT-1 Table 2.
Dose schedules: current FDA prescribing information for Wegovy and Zepbound.
Weight regain after stopping: Wilding JPH et al., Diabetes Obes Metab 2022 (STEP 1 extension).
Frequently Asked Questions
It applies the average result from the drug’s pivotal clinical trial to your starting weight. Wegovy (semaglutide 2.4 mg) uses STEP 1 (Wilding et al., NEJM 2021): an average −14.9% body weight at 68 weeks. Zepbound (tirzepatide) uses SURMOUNT-1 (Jastreboff et al., NEJM 2022): −15.0%, −19.5% and −20.9% at 72 weeks on 5, 10 and 15 mg. The papers only publish the week-by-week curve as a figure, so the shape between start and endpoint is a smooth model calibrated to the one interim result the trial reports numerically (about −12% by week 20 on tirzepatide 10–15 mg).
Yes. Choose “I’m already taking it”, enter your first-dose date and starting weight, and log a weigh-in whenever you like — weekly works best. The page plots you against the clinical-trial average, tells you whether you are ahead of or behind that pace, and makes a weekly check-in card you can post. Your entries are saved only in this browser on this device — nothing is uploaded — so come back on the same browser to continue. You can export them as a CSV or clear them at any time.
Trials report two kinds of averages. We use the “treatment-policy” result, which counts everyone who started, including people who stopped the drug. The “if taken as intended” result is higher: −16.9% for semaglutide 2.4 mg and −22.5% for tirzepatide 15 mg. Many articles quote the higher figure without saying which one it is. We stick to one kind throughout so the comparisons are fair.
Both are semaglutide. Ozempic is approved for type 2 diabetes at doses up to 2 mg; Wegovy is the version approved for weight management, at 2.4 mg in the STEP 1 trial used here. Mounjaro and Zepbound are likewise the same molecule (tirzepatide) approved for diabetes and weight respectively.
Individual results vary a lot around the average. The trials report what share of participants lost at least 5%, 10%, 15%, 20% (and for tirzepatide 25%) of their body weight. When you enter a goal, we show the share of trial participants who got there. Beyond the highest published threshold we can only say “fewer than” that share.
Weight tends to come back. In the STEP 1 extension (Wilding et al., Diabetes, Obesity and Metabolism 2022), participants regained about two-thirds of the weight they had lost within a year of stopping semaglutide, and cardiometabolic improvements largely reversed. These medications are intended as long-term treatment.
The trials enrolled adults with a BMI of 30 or more, or 27 or more with at least one weight-related condition such as high blood pressure, high cholesterol, type 2 diabetes, sleep apnea or heart disease — the same thresholds used in the original FDA approvals. Only a clinician can decide whether a medication is right for you.
Yes. Both drugs start low and step up every 4 weeks to reduce nausea: Wegovy reaches 2.4 mg at week 17, and Zepbound reaches 15 mg at week 21 at the earliest. Weight loss in the first weeks is therefore slower than later on, and many people stay on a lower dose if a higher one is not tolerated.