Semaglutide vs. Tirzepatide: Comparing the Research
Both semaglutide and tirzepatide are medications our physicians may consider. Each has published Phase 3 trial data from the New England Journal of Medicine. This article presents that data side by side based on the cited studies. The doctor determines which medication, if any, is appropriate for you. Individual results vary.
The Source Studies
All numbers in this article are drawn directly from:
- Wilding JPH et al. "Once-Weekly Semaglutide in Adults with Overweight or Obesity." NEJM. 2021;384:989–1002. (STEP 1 trial) — doi:10.1056/NEJMoa2032183
- Jastreboff AM et al. "Tirzepatide Once Weekly for the Treatment of Obesity." NEJM. 2022;387:205–216. (SURMOUNT-1 trial) — doi:10.1056/NEJMoa2206038
Side-by-Side: Trial Design
| Factor | Semaglutide (STEP 1) | Tirzepatide (SURMOUNT-1) |
|---|---|---|
| Published | NEJM, 2021 | NEJM, 2022 |
| Trial duration | 68 weeks | 72 weeks |
| Participants | 1,961 adults | 2,539 adults |
| Mechanism | GLP-1 receptor agonist | Dual GIP + GLP-1 receptor agonist |
| Administration | Once-weekly injection (2.4 mg) | Once-weekly injection (5, 10, or 15 mg) |
| T2D excluded? | Yes | Yes |
| Lifestyle intervention | Yes (all participants) | Yes (all participants) |
Side-by-Side: Mean Weight Reduction
Individual results vary. All figures are from the cited NEJM trials.
| Group | Mean weight reduction | Source |
|---|---|---|
| Semaglutide 2.4 mg (Wegovy®) | 14.9% | Wilding et al., NEJM 2021 |
| Placebo (STEP 1) | 2.4% | Wilding et al., NEJM 2021 |
| Tirzepatide 5 mg (Zepbound®) | 15.0% | Jastreboff et al., NEJM 2022 |
| Tirzepatide 10 mg (Zepbound®) | 19.5% | Jastreboff et al., NEJM 2022 |
| Tirzepatide 15 mg (Zepbound®) | 20.9% | Jastreboff et al., NEJM 2022 |
| Placebo (SURMOUNT-1) | 3.1% | Jastreboff et al., NEJM 2022 |
Important Caveats
These two trials were conducted independently, in different years, with different participant populations and slightly different trial durations. A direct head-to-head comparison would require a study that randomised participants to both agents simultaneously — which STEP 1 and SURMOUNT-1 did not do. The figures above are reported trial outcomes, not a controlled comparison of one drug against the other. Individual results vary.
What This Means for Your Program
Your Bunny physician reviews your individual health profile and determines which medication — if any — is appropriate for you. The doctor makes this decision. You will discuss your options during your consultation.
All medical decisions are made solely by licensed healthcare professionals. Medications are prescribed only when medically necessary. GLP-1 medications are not suitable for everyone. Results may vary.
Results vary. Clinical trial results apply only to the FDA-approved branded medication specifically identified and do not apply to compounded medications. All medications must be prescribed by a licensed provider based on medical necessity.