Peptides for weight loss: the GLP-1 class, compared.
Up to 24.2% average body-weight reduction in a published 48-week trial. We break down the two molecules behind the headlines, what the data says, and what a clean, lab-tested vial costs.
- Triple and dual agonists explained in plain English
- Every product checked for a third-party COA
- Free member registration unlocks volume savings
Research use only · 21+ · Not medical advice
🔥 Top weight-category compounds
Scored on purity documentation, published evidence, price per mg and shipping.
GLP-3RT Vial
★★★★★4.8/5 editorial scoreThe compound behind the biggest weight-trial numbers of the decade. Three receptors, one molecule, 13 lots with a COA on file.
GLP-2T Vial
★★★★★4.7/5 editorial scoreThe dual-agonist molecule with the deepest published record: 72-week data, a head-to-head win and the lowest price per mg in the catalog.
GLP-3RT Nasal Spray
★★★★☆4.2/5 editorial scoreSame triple-agonist compound in a pre-mixed nasal format. Convenient, but the published trials all used a different route.
What our editors say 🗣️
The compound behind the biggest weight-trial numbers of the decade. Three receptors, one molecule, 13 lots with a COA on file.
GLP-3RT VialThe dual-agonist molecule with the deepest published record: 72-week data, a head-to-head win and the lowest price per mg in the catalog.
GLP-2T VialSame triple-agonist compound in a pre-mixed nasal format. Convenient, but the published trials all used a different route.
GLP-3RT Nasal SprayThe dual agonist in a nasal spray. A smaller 20 mg version at $145 exists but was sold out at our last check.
GLP-2T Nasal SprayTriple agonist as an oral spray. The easiest format to handle, with the least published route data behind it.
GLP-3RT Oral SprayThe lowest-priced spray in the weight category. Dual agonist, oral spray format.
GLP-2T Oral SprayThese are our editors' scores against fixed criteria, reviewed by Sarah Mitchell, RD, CNS. They are not customer reviews.
Three generations, three curves 📈
One receptor, then two, then three. Each generation pushed the average result further in its own trial.
Average body-weight change at the top studied dose. Sources: STEP 1 (NEJM 2021), SURMOUNT-1 (NEJM 2022), retatrutide phase 2 (NEJM 2023). Separate trials, not a head-to-head comparison.
48 weeks, one curve ⏱️
Drag the slider or press play. The shape follows the average change reported for the top dose in the published 48-week triple-agonist study.
Published points: -17.5% at week 24 and -24.2% at week 48 (12 mg group, NEJM 2023). Values in between are interpolated. Trial averages in supervised participants, not a prediction for any person.
Real people, real videos 🙌
Sent in by customers. Unedited.
Individual experiences, not typical results and not a claim about any product. See all results →
One molecule, three switches
Tap a generation and watch which receptors light up.
All three on: appetite, blood sugar and energy expenditure. -24.2% average at 48 weeks in its phase 2 trial.
Find your match
What matters most to you? 🤔
Which format? 🧪
Budget for a first order? 💵
🎉 Your match
US Peptide Labs vs popular brands
What three US suppliers publish about their triple-agonist listing.
| 🇺🇸 US Peptide Labs | American Peptides | Real Peptides | |
|---|---|---|---|
| Triple-agonist listing | GLP-3RT | AP-RTA-3 | GLP3-RT (Trinity-X) |
| Starting price | $100 (10 mg) | from $105 | $4.99 per mg (sale price) |
| Vial sizes | 10, 20, 40 mg | 10 to 60 mg lots | 10, 20, 30 mg |
| Lowest listed price per mg | $7.50 (40 mg vial) | not listed per size | $4.99 (sale) |
| Stated purity | 99%+ | 99%+ | 99.29% (COA) |
| Outside lab named | AxisPharm | Bioviridian | Freedom Diagnostics, Kovera |
| COA per lot | Yes | Yes | Yes |
| QR code on the vial opens its COA | Yes | not stated | not stated |
| Nasal and oral spray formats | Yes, both | not listed | not listed |
| Free US shipping from | $70 | $300 | $250 |
| Ships from | US facility | Louisiana | Florida and California |
Figures as listed on each store's own website on November 10, 2026. Prices and sales change, so check before ordering. "Not stated" means we did not find it on their site.
🛍️ Shop by what you need
⭐ How we score
Four criteria, the same for every compound.
🧪 Purity & COA
Is there a lot-specific certificate from an outside lab, and can you pull it up yourself?
📚 Published evidence
How much peer-reviewed human data exists for the molecule, and for this exact format?
💵 Price per mg
Sticker price means little. We divide by milligrams and apply volume tiers.
🚚 Shipping
Where it ships from, whether it is tracked, and whether it crosses customs.
Scores are reviewed by Sarah Mitchell, RD, CNS. Meet the reviewers →
💬 Quick answers
Which peptide is studied most for weight loss?
The GLP-1 class. In published trials the dual agonist tirzepatide averaged -20.9% body weight at 72 weeks and the triple agonist retatrutide averaged -24.2% at 48 weeks at the top doses. US Peptide Labs lists these molecules for research as GLP-2T and GLP-3RT.
What is the difference between GLP-3RT and GLP-2T?
GLP-2T acts on two receptors (GLP-1 and GIP). GLP-3RT adds a third, glucagon, which is linked to energy expenditure. GLP-2T has the longer published record, GLP-3RT has the larger trial numbers so far.
Are these compounds FDA approved?
No. The compounds sold by US Peptide Labs are research chemicals for laboratory use. The triple agonist molecule is still investigational, with an FDA submission planned by its developer for early 2027.
Why US Peptide Labs?
Every lot gets an independent certificate of analysis from AxisPharm, each vial carries a QR code that opens its COA, and orders ship tracked from a US facility without crossing customs.
How do member savings work?
Register for free and your cart shows the store's volume pricing: 5% off 2 or more vials and 10% off 5 or more.