How Much Weight Loss Can You Expect on GLP-1s? Trial Data vs Real World
What clinical trials report for GLP-1 weight loss versus what patients see in the real world, and why adherence and care quality drive the gap.
How much weight will I lose on a GLP-1 medication?
Clinical trials report average weight loss of roughly 15% with semaglutide (STEP 1) and up to about 20% with tirzepatide (SURMOUNT-1; SURMOUNT-5), over 68–72 weeks with lifestyle support. Real-world results are often lower, mainly because of earlier discontinuation, lower doses, and less structured support. Individual results vary widely.
Disclaimer: American Telehealth Review is an editorial resource and does not provide medical advice, diagnosis, or treatment. Compounded medications are not FDA-approved finished drug products and should only be prescribed when clinically appropriate by a licensed healthcare provider. Brand-name medications such as Ozempic, Wegovy, Mounjaro, and Zepbound are FDA-approved under their own applications. Compounded semaglutide and compounded tirzepatide are not FDA-approved finished drug products.
Why real-world results differ
Trials maximize adherence, titration, and support. In practice, side effects, cost, and gaps in follow-up lead some patients to stop early or stay on lower doses, reducing average loss. Structured support and continuity of care narrow the gap.
What to look for in a program
Programs with clinician oversight, titration guidance, and included support tend to track closer to trial results. Compare oversight and true monthly cost, and review our methodology.
Mean weight loss in pivotal GLP-1 trials
| Medication | Trial (year) | Mean weight loss |
|---|---|---|
| Tirzepatide 15 mg | SURMOUNT-1 (2022) | 20.9% |
| Tirzepatide | SURMOUNT-5 (2025) | 20.2% |
| Semaglutide 2.4 mg | STEP 1 (2021) | 14.9% |
| Semaglutide 2.4 mg | SURMOUNT-5 (2025) | 13.7% |
| Oral semaglutide 25 mg | OASIS-4 (2025) | 13.6% |
| Oral orforglipron 36 mg | ATTAIN-1 (2025) | 12.4% |
Data shown in the chart above. Compounded versions are not the FDA-approved products studied in these trials.
Frequently asked questions
Why is my weight loss less than the trials?
Real-world loss is often lower due to early discontinuation, lower doses, and less structured support than trials provide.
How can I get closer to trial results?
Consistent dosing, clinician follow-up, and behavioral support help; results still vary by individual.
Sources
- Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021.
- Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med. 2022.
- Aronne LJ et al. Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5). N Engl J Med. 2025.