How Much Weight Will I Lose on a GLP-1?
Enter your weight and dose to project your expected loss on semaglutide (Wegovy) or tirzepatide (Zepbound) — using the actual average results from the pivotal clinical trials, not marketing numbers.
1. Medication
2. Weekly maintenance dose
3. Your current weight
Educational estimate only, based on published trial averages — not a prediction of your personal result, and not medical advice. Weight loss depends on your dose, how long you stay on it, side-effect tolerance, diet, and activity. Discuss any medication with a licensed clinician.
How this projection works
This tool doesn't guess. It applies the average total body-weight reduction measured in each medication's pivotal randomized trial to your starting weight.
For semaglutide, that's the STEP 1 trial: adults with overweight or obesity (without diabetes) lost an average of 14.9% of body weight on the 2.4 mg dose over 68 weeks, versus 2.4% on placebo.
For tirzepatide, that's SURMOUNT-1: average losses of 15% (5 mg), 19.5% (10 mg), and 20.9% (15 mg) over 72 weeks, versus about 3% on placebo — the largest average reductions seen with any approved anti-obesity medication to date.
Because people at the same dose had very different outcomes, the calculator also shows a realistic range rather than a single number. Real-world results are often a little below trial results, since trials support adherence closely.
A number on the scale isn't the whole story. Up to 40% of weight lost on a GLP-1 can be muscle if you don't protect it. Pair any projection with enough protein and resistance training, and track fat vs. muscle — not just weight.
Frequently Asked Questions
Sources
- Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1)Wilding JPH, Batterham RL, Calanna S, et al. N Engl J Med. 2021;384(11):989–1002. doi:10.1056/NEJMoa2032183
- Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)Jastreboff AM, Aronne LJ, Ahmad NN, et al. N Engl J Med. 2022;387(3):205–216. doi:10.1056/NEJMoa2206038
- Wegovy (semaglutide) Prescribing InformationU.S. Food & Drug Administration (FDA). 2023.
- Zepbound (tirzepatide) Prescribing InformationU.S. Food & Drug Administration (FDA). 2023.
Tool Information
July 24, 2026
Dr. Jaydeep Sanghani
Meet Akabari
Dr. Jaydeep Sanghani
MBBS, MD, DNB(Anaesth.), PDCC(CCM), DrNB(CCM)
AIIMS Bhubaneswar · AIIMS Rishikesh
Critical care specialist and anesthesiologist with advanced training from AIIMS. Reviews health calculators at Calqulate to ensure medical accuracy and evidence-based standards.