GLP-1 peptides: a careful primer
Retatrutide, tirzepatide and semaglutide — what they are, how they differ, and how to access them safely and legally.
What are GLP-1 peptides?
GLP-1 (glucagon-like peptide-1) receptor agonists are prescription medications that mimic a natural gut hormone to regulate blood sugar and appetite. Developed first for type 2 diabetes, several are now FDA-approved for chronic weight management.
How they work
GLP-1 agonists slow gastric emptying, prompt insulin release when blood sugar rises, and signal fullness in the brain — so you eat less and feel satisfied longer. Newer molecules add a second or third hormone target for stronger effects.
Semaglutide vs tirzepatide vs retatrutide
| Drug | Hormone targets | Status |
|---|---|---|
| Semaglutide (Wegovy / Ozempic) | GLP-1 | FDA-approved |
| Tirzepatide (Zepbound / Mounjaro) | GLP-1 + GIP | FDA-approved |
| Retatrutide | GLP-1 + GIP + glucagon | Investigational (Phase 3) |
What the clinical trials show
- Semaglutide — the STEP 1 trial reported roughly 15% average body-weight reduction over 68 weeks.
- Tirzepatide — SURMOUNT-1 reported up to ~21% at the highest dose.
- Retatrutide — a Phase 2 trial showed about 24% at 48 weeks, but it is not yet approved and not legally available for sale.
Side effects
Most side effects are gastrointestinal — nausea, diarrhea, constipation — and typically ease over time. Rarer risks include pancreatitis and gallbladder issues. These are prescription drugs and require medical supervision.
How to access GLP-1s legally
GLP-1s are prescription medications. The only safe, legal route is a licensed medical provider. Avoid "research use only" peptide vials sold online — they are unapproved, unregulated, and not legal for human use. We can connect you with vetted telehealth partners who prescribe and dispense legitimately.
Frequently asked
Is tirzepatide stronger than semaglutide?
In trial data, tirzepatide produced greater average weight loss, likely due to its dual GLP-1/GIP action.
What is retatrutide?
An investigational triple agonist (GLP-1/GIP/glucagon) in Phase 3 trials — promising, but not approved or legally for sale.
Can I buy GLP-1 peptides online?
Not legally as "research" vials. Obtain them through a licensed prescriber only.
Sources
- Wilding et al., STEP 1, New England Journal of Medicine, 2021.
- Jastreboff et al., SURMOUNT-1, New England Journal of Medicine, 2022.
- Jastreboff et al., Retatrutide Phase 2, New England Journal of Medicine, 2023.
Need a prescription option?
Prescription peptides should only be obtained through a licensed medical provider. We can connect you with vetted telehealth partners who handle this legally and safely.
Find a licensed providerEducational content only — not medical advice. We may earn a commission from licensed-provider referrals. *Statements about supplements have not been evaluated by the FDA.