If you’ve been researching medical weight loss, two names come up again and again: semaglutide and tirzepatide. Both are once-weekly injections, both are backed by large clinical trials, and both are offered at Evolv Wellness MedSpa in Aurora/Denver. So which one is right for you? Here’s a plain-language comparison.
How they work
Semaglutide is a GLP-1 receptor agonist. It mimics a natural gut hormone (GLP-1) that tells your brain you’re full, slows how quickly your stomach empties, and helps regulate blood sugar. The result for most people is smaller appetite, fewer cravings and less “food noise.”
Tirzepatide is a dual GIP and GLP-1 receptor agonist. It does everything a GLP-1 does, and it also activates a second hormone pathway (GIP) that plays a role in appetite and how the body handles sugar and fat. That two-pathway action is the main reason it has produced larger average weight loss in studies.
What the research shows
- Semaglutide: In the STEP-1 trial, adults taking semaglutide 2.4 mg weekly lost about 15% of their body weight on average over 68 weeks, alongside lifestyle changes.
- Tirzepatide: In the SURMOUNT-1 trial, adults on the highest dose lost about 21% of their body weight on average over 72 weeks.
- Head to head: In SURMOUNT-5, which compared the two directly, people on tirzepatide lost about 20% of their body weight on average versus about 14% on semaglutide.
Averages aren’t guarantees. Some people respond better to one medication than the other, and results depend on dose, consistency, nutrition, activity and sleep.
Side effects
Both medications share a similar side-effect profile, mostly digestive: nausea, constipation, diarrhea or reduced appetite, usually strongest when you start or increase a dose. We start low and increase gradually to keep you comfortable. Neither medication is appropriate for people with a personal or family history of medullary thyroid carcinoma or MEN2, or for anyone who is pregnant or planning a pregnancy. Your provider will review your health history before prescribing.
Semaglutide vs. tirzepatide at a glance
| Semaglutide | Tirzepatide | |
|---|---|---|
| Type | GLP-1 agonist | Dual GIP + GLP-1 agonist |
| Dosing | Once weekly injection | Once weekly injection |
| Average weight loss in trials | About 15% | Up to about 21% |
| Common side effects | Nausea, GI upset | Nausea, GI upset |
| Good fit for | A proven, well-studied starting point | People wanting a stronger effect, or who plateaued on a GLP-1 |
Which one is right for you?
There’s no one-size-fits-all answer. Generally, GLP-1 medications are considered for adults with a BMI of 30 or higher, or 27 or higher with a weight-related condition such as high blood pressure or prediabetes. During your consultation we’ll look at your goals, health history, any past experience with weight-loss medication and your budget, then recommend the option that makes the most sense. Many patients start on one and switch later if their needs change.
Learn more on our Semaglutide Weight Loss and Medical Weight Loss pages. Interested in supporting results with recovery, energy or body-composition peptides? See Peptide Therapy & NAD+.
Start your weight-loss plan
Ready to start? Book your consultation at Evolv Wellness MedSpa, 2503 Elmira Street, Aurora, CO 80010.
This article is for educational purposes and isn’t medical advice. Talk with a licensed provider about whether these medications are right for you.
Related reading: Peptides for Weight Loss · Medical Weight Loss at Evolv