Weight loss projection (2026): what the trials say you’ll lose
A Wegovy weight loss calculator that also covers Zepbound and Ozempic. It projects loss from trial averages and shows the published figure for stopping.
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To lose more than 17%: tirzepatide
Only tirzepatide 15 mg averaged more than 20% (SURMOUNT-1). The semaglutide average is below 17%.
To lose 10% to 17%: semaglutide 2.4 mg or tirzepatide
Both trial averages cover this range. Price and side effects usually decide. The cost calculator shows the price.
To lose less than 10%: more options
Lower doses give lower averages. The cheapest option may be enough.
Stopping is the weak point
In the STEP 1 extension, two-thirds of the lost weight came back within 1 year. Plan how to keep it off before you start.
Wegovy (semaglutide 2.4 mg): 14.9% average loss
STEP 1, 68 wk · NCT03548935
Zepbound / Mounjaro (tirzepatide 15 mg): 20.9% average loss
SURMOUNT-1, 72 wk · NCT04184622
Ozempic (semaglutide 1 mg, diabetes dosing): 7.0% average loss
STEP 2, 68 wk (semaglutide 1.0 mg, type 2 diabetes) · NCT03552757. Diabetes dosing loses materially less than Wegovy 2.4 mg.
Compounded semaglutide: 14.9% average loss
Anchored to STEP 1 · NCT03548935. Assumes titration to a 2.4 mg-equivalent dose.
Compounded tirzepatide: 20.9% average loss
Anchored to SURMOUNT-1 · NCT04184622. Assumes titration to a 15 mg-equivalent dose.
Tirzepatide against semaglutide: 20.2% against 13.7%
Source: peer-reviewed primary publications (NEJM, Lancet), checked October 25, 2026. The Ozempic curve uses semaglutide 1 mg in people with type 2 diabetes (STEP 2), which gave much less loss than Wegovy 2.4 mg.
Each curve starts from the average total loss in that medicine’s main trial: STEP 1 for semaglutide 2.4 mg and SURMOUNT-1 for tirzepatide. In this model, loss is fast at first and then flattens: about 70% of it comes by month 6 and about 95% by month 15. The formula is: percent lost at month t = L × M × (1 − e−0.21t).
L is the trial average. M is the diet and exercise factor (Minimal 0.85, Moderate 1.00, High 1.15). All the trials included diet and activity support, so Moderate is the trial average itself. The other settings are our own adjustment, not trial figures.
The shaded area is 0.55× to 1.25× the average curve: our own allowance for how much people vary. The trials report averages, not this range. The stop scenario uses the STEP 1 extension: about two-thirds of the lost weight came back in the year after stopping.
| Month | Semaglutide 2.4 mg | Tirzepatide 15 mg |
|---|---|---|
| 1 | 2.8% | 4.0% |
| 3 | 7.0% | 9.8% |
| 6 | 10.7% | 15.0% |
| 9 | 12.6% | 17.7% |
| 12 | 13.7% | 19.2% |
| 18 | 14.6% | 20.4% |
| 24 | 14.8% | 20.8% |
Limits: most trial patients had a BMI of 30 or more and no diabetes, unless noted. You may differ. People take their doses less regularly in real life than in trials. Compounded results assume you reach the same dose as the brand. This is an estimate for education. Your prescriber makes the treatment decisions.
“At trial-average response, a 220 lb adult on Wegovy projects to about 190 lb at month 12 (−13.7%), anchored to STEP 1, 68 wk” — glp1.health weight loss projection, glp1.health/tools/weight-loss-projection, data as of October 25, 2026.
Weight loss projection questions
This is an estimate for education. It is not medical advice and not a promise of results. Talk to a licensed clinician before you start, stop or change a medicine.
- 1.FDA prescribing informationThe labels for every product a tool names, on the label holder’s own sitedailymed.nlm.nih.gov
- 2.Manufacturer cash programsNovoCare, LillyDirect and TrumpRx published self-pay pricestrumprx.gov
- 3.CMS NADACNational Average Drug Acquisition Cost, weekly filedata.medicaid.gov
NADAC figures are pharmacy acquisition costs, not retail prices and not what you will pay. This content is educational and is not medical advice.