Best GLP-1 for Weight Loss: 2026 Head-to-Head
In trials, tirzepatide produces the largest weight loss (~22% on the highest dose), followed by semaglutide (~15%), then liraglutide (~8%). Cost, tolerability, and individual factors can flip the ranking for any specific patient. Here is the full comparison.
Last updated May 1, 2026.
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Trial Data Ranking
| Drug | Trial | Dose | Duration | Mean weight loss |
|---|---|---|---|---|
| Retatrutide (pipeline) | Phase 3 (Lilly) | Highest | 48 weeks | ~24% |
| Tirzepatide (Zepbound) | SURMOUNT-1 | 15 mg weekly | 72 weeks | ~21–22% |
| Tirzepatide (Zepbound) | SURMOUNT-1 | 10 mg weekly | 72 weeks | ~19.5% |
| Tirzepatide (Zepbound) | SURMOUNT-1 | 5 mg weekly | 72 weeks | ~15.0% |
| Semaglutide (Wegovy) | STEP-1 | 2.4 mg weekly | 68 weeks | ~14.9% |
| Liraglutide (Saxenda) | SCALE | 3.0 mg daily | 56 weeks | ~8.0% |
| Naltrexone + bupropion | COR-I | Standard | 56 weeks | ~6.1% |
Retatrutide is in late-stage development and not yet FDA-approved as of this update. Among approved drugs, tirzepatide leads.
Wegovy vs Zepbound: Direct Comparison
SURMOUNT-1 (tirzepatide) and STEP-1 (semaglutide) used different populations and study designs, so direct comparison has caveats. The SURMOUNT-5 trial compared tirzepatide directly to semaglutide and reported greater weight loss with tirzepatide.
| Wegovy (semaglutide 2.4 mg) | Zepbound (tirzepatide 15 mg) | |
|---|---|---|
| Average weight loss in trials | ~15% | ~22% |
| Other indications | CV risk reduction | OSA in obesity |
| Dosing | Weekly | Weekly |
| GI side-effect profile | Similar | Similar |
| List cash price | $1,300+/mo | $1,000–1,350/mo |
| LillyDirect vials | No | Yes, $349–550/mo |
| Compounded option | $199–399/mo | $299–499/mo |
How to Choose for Yourself
- Maximum weight loss as priority: Tirzepatide (Zepbound or compounded tirzepatide).
- Strong cardiovascular history: Semaglutide has the strongest CV outcomes data (SELECT, SUSTAIN-6).
- Sleep apnea in obesity: Zepbound has FDA-approved indication.
- Cost sensitivity: Compounded semaglutide is the cheapest legal option ($199–399/mo).
- Insurance coverage: Whichever your plan covers — coverage rules trump small efficacy differences in practice.
- Past adverse events: If you've tried one GLP-1 with intolerable side effects, switching to the other class may help.
What "Best" Really Depends On
- Genetic and metabolic variability. A subset of patients are non-responders to one but respond to another.
- Adherence. The best GLP-1 is the one you'll actually take consistently. Tolerability matters.
- Pre-existing conditions. Diabetic eye disease, severe GI motility issues, kidney function all influence choice.
- Goals beyond weight. Glycemic control, cardiovascular protection, sleep apnea.
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Compounded vs Brand: Same Drug, Different Cost
For most patients, compounded semaglutide or tirzepatide delivers comparable effect to brand at significantly lower cost. The trade-off is regulatory: compounded products lack FDA manufacturing approval. Choose accredited compounding pharmacies through licensed telehealth platforms only.
What's Coming
- Retatrutide — triple agonist, ~24% weight loss in late-stage trials
- Orforglipron — oral, no peptide handling issues, easier supply
- Higher-dose oral semaglutide — 25 mg and 50 mg in trials for obesity
Frequently Asked Questions
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Related Reading
Sources
- Jastreboff et al. SURMOUNT-1. NEJM 2022.
- Wilding et al. STEP-1. NEJM 2021.
- Pi-Sunyer et al. SCALE. NEJM 2015.
- Aronne et al. SURMOUNT-5 (Tirzepatide vs Semaglutide). NEJM 2025.