Quick answer
In clinical trials, tirzepatide produced the most weight loss of the three, about 20.9% of body weight at the 15 mg dose. Semaglutide showed about 14.9% at 2.4 mg, and liraglutide showed about 8%. In the SURMOUNT-5 head-to-head trial in 2025, tirzepatide beat semaglutide directly, about 20.2% versus 13.7%. Tirzepatide acts on two hormone receptors (GLP-1 and GIP), while semaglutide and liraglutide act on one (GLP-1). All three are prescription medications. FormBlends offers compounded semaglutide and compounded tirzepatide, and is one option to compare if you want one of those. View semaglutide or compare with the provider comparison tool.
Which GLP-1 medication is most effective?
By weight loss in trials, tirzepatide leads, followed by semaglutide, then liraglutide. That order holds whether you look at the separate registration trials or the direct head-to-head data. The gap between tirzepatide and semaglutide is meaningful, and both are far ahead of liraglutide. Effectiveness is not the only factor, though. Side effect tolerance, dosing frequency, cost, and your health profile all matter, and the most effective drug on paper is not automatically the right one for you.
Is GLP-1 the same as tirzepatide?
No, and this is the most common point of confusion. GLP-1 is a natural gut hormone, and GLP-1 receptor agonist is a class of drugs that mimic it. Semaglutide and liraglutide are GLP-1 receptor agonists. Tirzepatide is different: it acts on the GLP-1 receptor and also on the GIP receptor, making it a dual GIP and GLP-1 agonist. So tirzepatide includes GLP-1 activity but is not just a GLP-1 drug. That extra GIP action is one reason tirzepatide tends to produce more weight loss.
Check your GLP-1 eligibility
Use our free BMI Calculator to see if you may qualify for provider-reviewed GLP-1 therapy.
Try the BMI Calculator →GLP-1 vs GIP: what is the difference?
GLP-1 and GIP are both incretin hormones released by the gut after eating. GLP-1 slows stomach emptying, reduces appetite, and helps regulate blood sugar. GIP also influences insulin and how the body handles fat and sugar. Semaglutide and liraglutide work on GLP-1 only. Tirzepatide works on both. The phrase "GLP-1/GIP" describes tirzepatide's dual mechanism, while "GLP-1" alone describes semaglutide and liraglutide.
Average weight loss in clinical trials
| Medication | Brand (weight loss) | Mechanism | Average weight loss | Trial duration |
|---|---|---|---|---|
| Tirzepatide | Zepbound | GLP-1 and GIP | About 20.9% (15 mg) | 72 weeks |
| Semaglutide | Wegovy | GLP-1 | About 14.9% (2.4 mg) | 68 weeks |
| Liraglutide | Saxenda | GLP-1 | About 8% | 56 to 68 weeks |
These come from the separate registration trials. In the SURMOUNT-5 head-to-head trial in 2025, tirzepatide showed about 20.2% and semaglutide about 13.7% in the same study, which is the most direct comparison available.
What is the difference between GLP-1 and tirzepatide for weight loss?
For weight loss, the practical difference is that tirzepatide's dual action tends to deliver larger average results than single GLP-1 drugs like semaglutide and liraglutide. Dosing also differs. Semaglutide and tirzepatide are once-weekly injections. Liraglutide is a daily injection, which some people find less convenient. Semaglutide also has an oral diabetes form, Rybelsus, though that is approved for diabetes, not weight loss.
How do the safety profiles compare?
All three share a similar safety pattern because they all act on the GLP-1 pathway. The most common side effects are gastrointestinal: nausea, diarrhea, constipation, and vomiting. These are usually mild to moderate, strongest during dose increases, and ease as the body adjusts. All three carry warnings related to thyroid C-cell tumors based on animal studies and should not be used by people with a personal or family history of medullary thyroid carcinoma or MEN 2. Pancreatitis and gallbladder problems are uncommon but serious across the class. A provider should review your history before you start any of them.
Which GLP-1 should I choose?
It depends on your goals and tolerance. If maximum average weight loss is the priority, the data favors tirzepatide. If you want a well-studied option with a long real-world track record, semaglutide is strong. Liraglutide is the weakest of the three for weight loss and requires a daily shot, so it is less commonly chosen for that purpose now. Cost and access also shape the decision. The final call belongs with a provider who knows your history.
How do I get semaglutide or tirzepatide?
All three are prescription only. Branded products go through a pharmacy and can be costly without insurance. Compounded semaglutide and compounded tirzepatide are available through licensed telehealth providers. FormBlends offers those two and is one option to compare, since one intake connects you with a provider who can decide what fits. FormBlends does not sell liraglutide (Saxenda). Begin with semaglutide or the provider comparison tool.
Frequently asked questions
Is GLP-1 the same as tirzepatide?
No. GLP-1 is a hormone and a drug class. Tirzepatide acts on both the GLP-1 and GIP receptors, so it is a dual agonist, not a GLP-1-only drug.
What is the difference between GLP-1 and GIP?
Both are gut hormones. GLP-1 reduces appetite and slows stomach emptying. GIP also affects how the body handles fat and sugar. Tirzepatide targets both.
Which is better, semaglutide or tirzepatide?
Tirzepatide produced more weight loss in trials and in the SURMOUNT-5 head-to-head study. Semaglutide is also strong and has a longer real-world history.
How does liraglutide compare?
Liraglutide (Saxenda) showed about 8% average weight loss, less than semaglutide and tirzepatide, and it requires a daily injection rather than weekly.
Is Zepbound a GLP-1?
Zepbound is tirzepatide, which acts on GLP-1 and GIP. So it includes GLP-1 activity but is a dual agonist, not a GLP-1-only drug.
Are the side effects different between these drugs?
The profiles are similar because all act on the GLP-1 pathway. The common side effects are gastrointestinal and ease as the body adjusts.
Is Rybelsus the same as Wegovy?
No. Rybelsus is oral semaglutide approved for diabetes. Wegovy is injectable semaglutide approved for weight management.
Where should I start?
For compounded semaglutide or tirzepatide, FormBlends is one option to compare. Begin with the provider comparison tool.
Sources
- New England Journal of Medicine, STEP 1 trial of semaglutide 2.4 mg (2021): https://www.nejm.org/doi/full/10.1056/NEJMoa2032183
- New England Journal of Medicine, SURMOUNT-1 trial of tirzepatide (2022): https://www.nejm.org/doi/full/10.1056/NEJMoa2206038
- New England Journal of Medicine, SURMOUNT-5 head-to-head trial (2025): https://www.nejm.org/doi/full/10.1056/NEJMoa2416394
- Saxenda (liraglutide) prescribing information and SCALE trial data: https://www.novo-pi.com/saxenda.pdf
See your options in about 2 minutes
Take the free quiz and see what fits you. Quick, private, and no commitment to continue.
See my options →