Retatrutide is Lilly’s triple-agonist peptide. GIP, GLP-1, and glucagon on one weekly pin. Code name LY3437943. In TRIUMPH-1 the 12mg arm lost an average of 70.3 lb (28.3%) in 80 weeks. Not a brand. Not a CVS pen. Searches land here as peptide, dosage, benefits, side effects, and vs tirzepatide.
Medical sites walk the trials and stop at “you cannot buy it.” This page holds the Lilly file and the research vial — often labeled GLP-3 RT or other names.
Everest GLP-3 RT is 10mg, 20mg, and 30mg, multi-panel third-party tested through Freedom Diagnostics, on sale from $52.49. Code BRAINFLOW is 10% off.
The BrainFlow Take
TRIUMPH-1 12mg: 70.3 lb, 28.3%, 80 weeks. 45.3% of that arm hit 30% loss. BMI ≥35 extension: 85.0 lb, 30.3% at 104 weeks. Liver-fat substudy −86% at 12mg. TRIUMPH-2 (diabetes) 20.8%. 12mg AE dropout in TRIUMPH-1 was 11.3%. Unapproved. BLA planned Q1 2027. Pharmacies cannot compound it. Research SKUs exist. Demand a COA.
LY3437943. Weekly subcutaneous. Not a pill.
70.3 lb at 80 weeks. NCT05929066.
BMI ≥35. 85.0 lb.
Sanyal Phase 2a. Nature Medicine 2024.
Looks ahead across trials. TRIUMPH-5 not out.
First-timers often 0.5–1mg. Trial start is 2mg.
Retatrutide Peptide: What It Actually Is
A synthetic peptide — a long engineered chain, not a tablet like orforglipron (Foundayo). Research catalogs call it Reta, GLP-3, or GLP-3 RT. Three class-B receptors at once. Do not swallow it. Weekly subcutaneous is the only route the trials used and the only route that makes sense for a lyophilized vial.
Wegovy and Zepbound are peptides too. They have pens and a label. Retatrutide has a Phase 3 file and a cake in a 3mL vial.
What Retatrutide Is Used For
Lilly is developing it for obesity and overweight with at least one weight-related condition. Phase 3 also ran type 2 diabetes (TRIUMPH-2), established cardiovascular disease (TRIUMPH-3), and knee osteoarthritis (TRIUMPH-4). A MASLD / liver-fat substudy already read out. Sleep apnea, chronic low-back pain, and a long outcomes trial are still in the stack.
There is no labeled indication. “Used for” in 2026 means “studied for.” People on the research market are running it as a weight-loss peptide. That is not a prescription use.
How Retatrutide Works
GLP-1 slows the stomach and raises satiety. GIP is the second incretin — the piece that let tirzepatide beat semaglutide in SURMOUNT-5. Glucagon is the third lock. In this design it leans on energy expenditure and how the liver handles fat. That is why the Phase 2 curve had not flattened at week 48, and why the MASLD numbers look different from a pure GLP-1. It is also why resting heart rate drifted up, peaked near week 24, then eased.
Retatrutide Benefits and Weight Loss Results
- Body weight. TRIUMPH-1 12mg, 80 weeks: 28.3%, 70.3 lb from a 248.5 lb baseline. 45.3% of that arm lost 30% or more. BMI ≥35 extension: 30.3%, 85.0 lb at 104 weeks.
- BMI class. 65.3% on 12mg crossed under 30. 37.5% who started at BMI ≥40 did the same.
- Waist, lipids, BP, inflammation. TRIUMPH-3 (CVD): triglycerides −37.0%, non-HDL −16.5%, systolic −9.3 mmHg, waist −7.5 inches, hsCRP −51.2%.
- Blood sugar. TRIUMPH-2: baseline A1C 7.7%, 12mg dropped about 1.5% (Lilly also reported drops to 1.6% in the set). Weight −20.8% / 49.6 lb.
- Knee osteoarthritis. TRIUMPH-4: 28.7% at 12mg, 68 weeks, pain and function scores moving with the weight.
- Liver fat. Phase 2a MASLD: −86% relative liver fat at 12mg, 48 weeks.
Not proven: fewer heart attacks. Outcomes trial runs into 2028–29.
Clinical Trials
Phase 2, Jastreboff, NEJM 2023, NCT04881760, 338 adults, 48 weeks. 12mg −24.2%. 100% of that arm lost ≥5%.
TRIUMPH-1, Lilly May 21, 2026, NCT05929066, 2,339 adults, no diabetes, 80 weeks. 4mg −19.0% (−47.2 lb). 9mg −25.9% (−64.4 lb). 12mg −28.3% (−70.3 lb).
TRIUMPH-4 (Dec 2025, NCT05931367): knee OA, 12mg −28.7% at 68 weeks. TRIUMPH-2 (July 23, 2026, NCT05929079): T2D + obesity, 12mg −20.8%. TRIUMPH-3 (NCT05882045): severe obesity + CVD, 12mg −22.6%. TRIUMPH-5 vs tirzepatide (NCT06662383) has not reported.
| Study | Who | 12mg result |
|---|---|---|
| Phase 2 NEJM | Obesity, 48 wks | 24.2% |
| TRIUMPH-1 | No diabetes, 80 wks | 28.3% / 70.3 lb |
| TRIUMPH-1 ext. | BMI ≥35, 104 wks | 30.3% / 85.0 lb |
| TRIUMPH-4 | Knee OA, 68 wks | 28.7% |
| TRIUMPH-2 | T2D + obesity, 80 wks | 20.8% / 49.6 lb |
| TRIUMPH-3 | CVD + severe obesity, 80 wks | 22.6% / 55.8 lb |
Catalog name · GLP-3 RT
Everest 10mg / 20mg / 30mg
Freedom Diagnostics HPLC, COA on the listing, sale from $52.49. Search GLP-3 RT. Code BRAINFLOW is 10% off any size.
Research use only. Prices move.
Liver Fat
Sanyal, Nature Medicine 2024, same NCT04881760 cohort. 98 people, liver fat ≥10%. At 24 weeks 12mg −82.4% relative liver fat; at 48 weeks −86.0%. Normal liver fat (
Retatrutide vs Tirzepatide, Wegovy, and Foundayo
| Wegovy (sema) | Zepbound (tirz) | Foundayo (orfor) | Retatrutide | |
|---|---|---|---|---|
| Receptors | GLP-1 | GIP + GLP-1 | GLP-1 (pill) | GIP + GLP-1 + glucagon |
| Route | Weekly pin | Weekly pin | Daily tablet | Weekly pin |
| Headline loss | ~15% STEP-1 | ~21% SURMOUNT-1 | Oral GLP-1 file | 28.3% TRIUMPH-1 |
| FDA | Approved | Approved | Approved | File Q1 2027 |
| Pharmacy | Yes | Yes | Yes | No |
Cross-trial, retatrutide looks ahead of Zepbound. TRIUMPH-5 is the head-to-head (NCT06662383). Not out. Foundayo is Lilly’s oral GLP-1 — different job, different patient. Nobody serious picks Wegovy over retatrutide for ceiling. They pick a label they can fill this week.
Coming off Mounjaro, people usually land at 2–4mg of retatrutide, not at 0.5mg. First-timers with no GLP-1 history are the 0.5–1mg crowd.
Retatrutide Dosage
Once weekly, same day, subcutaneous. Half-life ~6 days. Phase 3 starts at 2mg, steps every four weeks: 2 → 4 → 6 → 9 → 12. Forums screenshot 1 → 2 → 4 → 8 → 12. Hold a rung if the gut is still loud. Speeding up is how people dropped out.
| Weeks | Phase 3 | Forum chart |
|---|---|---|
| 1–4 | 2mg | 1mg (or 0.5) |
| 5–8 | 4mg | 2mg |
| 9–12 | 6mg | 4mg |
| 13–16 | 9mg | 8mg |
| 17+ | 12mg or hold 9 | 12mg |
| Dose | 10mg + 2.0 mL | 30mg + 3.0 mL |
|---|---|---|
| 1mg | 20 units | 10 units |
| 2mg | 40 units | 20 units |
| 4mg | 80 units | 40 units |
| 8mg | 160 units | 80 units |
| 12mg | Split draws | 120 units |
How Long Does Retatrutide Take to Work?
Appetite usually moves in the first two to four weeks. Scale weight in the trials is a months-long slope, not a ten-day miracle. Phase 2 already had double-digit percent by week 24 at the higher arms. TRIUMPH-1 kept falling through week 80, and the BMI ≥35 extension was still adding loss at week 104. If the only question is “will I feel it this week,” the answer is the gut and the fork, not the 70-pound headline.
Retatrutide Side Effects
Nausea, diarrhea, vomiting, constipation, appetite collapse. Worst after a step-up. TRIUMPH-1 stop-for-AE: 4.1% at 4mg, 6.9% at 9mg, 11.3% at 12mg, 4.9% placebo. TRIUMPH-2 12mg: 7.7%. TRIUMPH-3 12mg: 13.5%. Dysesthesia (odd skin or nerve buzz) and mild UTIs showed up and usually did not end the trial. Heart rate drifted up, peaked around week 24, then eased.
Class cautions: personal or family MTC or MEN2, prior serious GLP-1 reaction, pregnancy. Pancreatitis history, bad gastroparesis, active gallbladder, rough kidneys — clinician, not a poll.
FDA Status, Cost, and When It Will Be Available
Not approved. No trade name. Lilly said July 23, 2026 it will file a BLA in Q1 2027. If they file on time, a decision is late 2027 or 2028. There is no commercial price because there is no product. A compounding pharmacy cannot fill it — never approved, never on the shortage list. September 2025 FDA letters hit sellers making treatment claims.
Research vials are a different market. That is the $52.49 conversation, not a list price from Lilly.
Where to Buy Retatrutide Peptide
No chromatogram, no buy. Everest titles it GLP-3 RT, 10 / 20 / 30mg, Freedom Diagnostics, 99%+, COA on the listing, sale from $52.49. Code BRAINFLOW takes 10% off the sale.
Tested triple · sale price
GLP-3 RT at Everest
10mg, 20mg, 30mg. Search that name. Code BRAINFLOW is 10% off.
Get GLP-3 RT →FAQ
Is retatrutide FDA approved?
No. Lilly plans to file Q1 2027.
Is retatrutide a GLP-1?
It hits GLP-1 plus GIP plus glucagon. Calling it “a GLP-1” is half the molecule.
Is retatrutide the same as Ozempic?
No. Ozempic is semaglutide, GLP-1 only, approved. Retatrutide is a triple, unapproved.
How much weight can you lose?
TRIUMPH-1 12mg averaged 70.3 lb (28.3%) at 80 weeks. Extension 85.0 lb at 104 weeks in BMI ≥35.
How long does it take to work?
Appetite in weeks. The 70-pound headline is 80 weeks.
Retatrutide vs tirzepatide?
Cross-trial it looks ahead. TRIUMPH-5 is the head-to-head. Not out.
What is GLP-3 RT?
Catalog name for research-grade retatrutide. 10 / 20 / 30mg.
Bottom Line
70.3 lb at 80 weeks is the number. The liver-fat drop is the sleeper. The glucagon arm is the reason both exist. Still a research chemical in the US. Mix milligrams, not whole vials. Buy a ticket you can open.
Everest GLP-3 RT — 10mg / 20mg / 30mg — code BRAINFLOW saves 10%
Retatrutide is investigational and not FDA-approved. Research compounds are sold for laboratory use only. Not pharmacy-compoundable. Educational, not medical advice. Sources: Jastreboff NEJM 2023 (NCT04881760); Sanyal Nature Medicine 2024; Lilly TRIUMPH-1 NCT05929066 (May 21, 2026); TRIUMPH-2 NCT05929079 / TRIUMPH-3 NCT05882045 (July 23, 2026); TRIUMPH-4 NCT05931367 (Dec 2025).
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Last updated: September 2026
