Trial review
STEP-8: Semaglutide Against Liraglutide, Head to Head
How does weekly semaglutide compare with daily liraglutide for weight loss?
Direct answer
STEP-8 was a randomised, open-label, active-comparator, phase 3b funded by Novo Nordisk. Mean weight change approximately −15.8% on semaglutide against approximately −6.4% on liraglutide and −1.9% on placebo. That figure belongs to the population, dose and 68 weeks shown below, and describes a group average rather than a prediction for any individual.
STEP-8 at a glancepublished, peer-reviewed
| Design | Randomised, open-label, active-comparator, phase 3b |
|---|---|
| Population | Adults with BMI 30 or above, or 27 or above with a comorbidity, without diabetes |
| Sample size | 338 |
| Intervention | Semaglutide 2.4 mg weekly |
| Comparator | Liraglutide 3.0 mg daily, and placebo |
| Duration | 68 weeks |
| Primary endpoint | Percentage change in body weight |
| Main result | Mean weight change approximately −15.8% on semaglutide against approximately −6.4% on liraglutide and −1.9% on placebo |
NCT NCT04074161 · DOI 10.1001/jama.2021.23619 · PMID 35015037Last source check: 2026-08-03
Show this figure as a table
| Step | Stage | What happens |
|---|---|---|
| 1 | Who was eligible | Adults with BMI 30 or above, or 27 or above with a comorbidity, without diabetes |
| 2 | What they received | Semaglutide 2.4 mg weekly |
| 3 | What it was compared against | Liraglutide 3.0 mg daily, and placebo |
| 4 | For how long | 68 weeks |
| 5 | What was measured first | Percentage change in body weight |
| 6 | What the group average was | Mean weight change approximately −15.8% on semaglutide against approximately −6.4% on liraglutide and −1.9% on placebo |
| 7 | What it does not tell you | A group average is not a prediction for any individual reader. |
Strip any step and the result stops meaning what the trial found.
Show this figure as a table
| Item | Weight change | Evidence |
|---|---|---|
| Semaglutide 2.4 mg | 16% | published, peer-reviewed |
| Liraglutide 3.0 mg | 6% | published, peer-reviewed |
| Placebo | 2% | published, peer-reviewed |
Group means under trial conditions with lifestyle intervention. Not a prediction for any individual reader.
Show this figure as a table
| Item | Mean reduction | Evidence |
|---|---|---|
| Tirzepatide 15 mg (SURMOUNT-1) | 21% | Verified |
| Oral semaglutide 25 mg, adherent (OASIS 4) | 17% | Verified |
| Injectable semaglutide 2.4 mg (SURMOUNT-5) | 14% | Verified |
| Oral semaglutide 25 mg, treatment-policy (OASIS 4) | 14% | Verified |
| Orforglipron 17.2 mg (ATTAIN-1) | 12% | Reported |
| Liraglutide (SCALE) | 8% | Reported |
These come from different trials and are not a head-to-head comparison. Durations differ (64 to 72 weeks) and estimands differ. Only SURMOUNT-5 compared two of these drugs directly.
| Product | Starting self-pay price | Reported mean reduction | Trial |
|---|---|---|---|
| Zepbound (tirzepatide) injectable | $299/mo direct | about 20.9% at 15 mg | SURMOUNT-1, 72 weeks |
| Wegovy pill (oral semaglutide 25 mg) | $149/mo starting dose | 13.6–16.6% depending on estimand | OASIS 4, 64 weeks |
| Wegovy injectable (semaglutide 2.4 mg) | $349/mo maintenance | about 13.7% | SURMOUNT-5, 72 weeks |
| Foundayo (orforglipron) | $149/mo starting dose | about 11–12.4% at 17.2 mg | ATTAIN-1, 72 weeks |
Both $149 products are the least effective approved options in this table. That does not make them bad choices — it makes a price comparison that omits efficacy an incomplete one.
Frequently asked questions
Does this apply to compounded versions?
No. The trial studied an FDA-approved product at studied doses.
Is this drug as effective as tirzepatide?
By mean reduction across separate trials, no. The efficacy ladder above sets out the figures with the trial that produced each one.
Related on this site
- Research hubResearch
- SURMOUNT-1 Tirzepatide Trial ExplainedResearch
- SURMOUNT-3 Tirzepatide Trial ExplainedResearch
- SURMOUNT-4: Weight Maintenance and Tirzepatide WithdrawalResearch
- How rankings are computedCore & Trust
- All-in cost toolTools
- Price records, machine-readableData
- Tirzepatide Clinical Trial FinderTools
- SURPASS-2: Tirzepatide vs Semaglutide in Type 2 DiabetesResearch
- SURMOUNT-OSA and Tirzepatide for Sleep ApneaResearch
Related coverage
Cite this pageCC BY 4.0
GLP-1 Tirzepatide Rank. “STEP-8: Semaglutide Against Liraglutide, Head to Head.” S.J Partners LLC, 2026-08-03. https://glp1tirzepatiderank.com/research/step-8/
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