What this calculator estimates
This tool projects your potential weight loss on each GLP-1 by applying that drug’s average clinical-trial result to your current weight. It’s the fastest way to see the difference between the medications in real pounds — not just abstract percentages — and to set a realistic expectation before you start.
The key word is average. Every number here comes from a large clinical trial, and in those trials some people lost dramatically more than the average while others lost relatively little. Your result sits somewhere in a range, which is why the calculator shows a band, not just a single figure.
The trial numbers behind it
Each medication’s estimate is anchored to its main study:
| Medication | Average loss | Trial |
|---|---|---|
| Zepbound (tirzepatide 15 mg) | ~21% | SURMOUNT-1, 72 weeks |
| Wegovy (semaglutide 2.4 mg) | ~15% | STEP 1, 68 weeks |
| Saxenda (liraglutide 3 mg) | ~8% | SCALE, 56 weeks |
| Mounjaro* (tirzepatide) | ~21% | same molecule as Zepbound |
| Ozempic* (semaglutide) | ~6% | diabetes-dose trials |
* Mounjaro, Ozempic, Rybelsus, Victoza, and Trulicity are FDA-approved for type 2 diabetes, not weight loss. Their figures are approximate — drawn from diabetes trials or the same-molecule obesity trial — and shown for education only.
Two things stand out. First, tirzepatide (Zepbound/Mounjaro) leads the pack — its ~21% average is territory that used to require surgery. Second, the same molecule can show very different numbers: Wegovy and Ozempic are both semaglutide, but Wegovy’s higher obesity-trial dose produces roughly double Ozempic’s diabetes-trial average.
Why your real result will differ
A calculator can’t know your biology, so treat the output as a reasonable expectation, not a promise. The biggest factors that move you within (or beyond) the range:
- Dose reached. The trial averages assume you titrate up to and stay at the studied maintenance dose. People who stop climbing early tend to lose less.
- Time. These results unfold over 12–18 months, not weeks. The early months are dose-ramp months.
- Diet, protein, activity, and sleep. The trials paired the drug with lifestyle support for a reason — the medication works best as a floor for your appetite, not a replacement for the basics. Protecting muscle with enough protein also shapes how good the loss looks and feels.
- Consistency and staying on it. Trial extensions show much of the weight returns after stopping, so durability depends on maintenance.
Using it well
Use this to compare medications and set expectations, then track reality against it with the weight-loss percentage calculator once you start. If the numbers make a GLP-1 feel worth exploring, the next questions are whether you qualify and how to get one — a licensed provider decides what’s appropriate for you. This tool is educational and not medical advice.