Retatrutide
Monograph · AGLP-1/GIP/glucagon triple agonist — the only triple-receptor GLP-1 agent in Phase 3. Largest weight-loss signal ever recorded in a Phase 3 RCT: 28.7% body weight reduction at 68 weeks (TRIUMPH-4, 12 mg).
How it clearsHalf cleared in ~7d. Most (~96%) gone by ~35d.
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Mechanism, evidence, legal path, cost — all side-by-side.
This compound sits in research-grey territory. The caveats below carry more weight than for FDA-approved entries — read them.
Eli Lilly investigational peptide that simultaneously activates three incretin/glucagon receptors: GLP-1R (satiety + insulin secretion), GIPR (additive weight loss), and GCGR (energy expenditure + liver fat mobilization). The triple mechanism explains the outsized weight-loss signal compared to dual agonists like tirzepatide — GCGR activation drives additional fat mobilization beyond what GLP-1 + GIP alone achieve. TRIUMPH-4 (Phase 3, 68 weeks, knee osteoarthritis cohort): 28.7% mean body weight reduction at 12 mg, WOMAC knee pain -4.4 vs -2.4 placebo. Seven additional TRIUMPH Phase 3 readouts expected through 2026. Not FDA-approved as of 2026-05-07. Grey-market supply is essentially non-existent — compound is too new and synthesis complexity is high.
Emerging metabolic evidence with a real mechanistic basis — but the dose-response curve is wider than in established compounds. The first 3–4 weeks should be treated as response-threshold discovery, not outcome measurement. Individual variation here is a feature of the tier, not a flaw in the compound.
GI side effects (nausea, vomiting, diarrhea) are the class-wide risk — dose titration is required; no approved titration schedule exists outside clinical trials. Psychological / motivational side effects reported anecdotally (blunted reward, emotional flatness) — not yet systematically studied but consistent with the broader GLP-1 class signal. Sponsor-funded trial design: Lilly funded all TRIUMPH trials — treat weight-loss % claims as B-grade until independent replication.
Aib at position 2; fatty acid acylation. Triple agonist sequence engineered for GIP/GLP-1/glucagon receptor activity.
Known risk or pharmacological conflict.
Upload a lab file (LabCorp / Quest) or DNA file (23andMe / AncestryDNA). Stack will show your specific markers alongside the literature-reported response windows.
Upload in /historyStack doesn't rank peptides — we surface the diversity of opinion. Each card paraphrases a public-record stance from a named source. Where they conflict is where you should slow down and read both.
Phase 2 TRIUMPH-1 (NEJM 2023) showed ~24% body-weight reduction at 48 weeks at maximum dose — larger than any other approved or pending obesity drug. Triple agonism at GLP-1 + GIP + glucagon receptors. Phase 3 ongoing with FDA approval expected late 2026 / early 2027.
Source →S-tier — top of his peptide ranking. "GLP-3 — three receptors, suppresses appetite AND accelerates metabolism. I've been taking Reta for about a year. Reduces food noise without hunger suppression to the point of nausea." Has used personally for 12+ months.
Pre-FDA-approval, Retatrutide use by patients is research-grey only. Several telehealth platforms paused compounded-Reta access after Eli Lilly's April 2025 lawsuits against compounders. Until FDA approval lands, all Retatrutide access carries quality + legal exposure that exceeds Tirzepatide-era compounding.
Per-claim grading. Each claim is graded independently — same peptide, different claims can carry different grades.
External links to PubMed searches, ClinicalTrials.gov, and FDA materials. We do not host papers — we point at canonical sources.
Not FDA-approved. Investigational drug (Eli Lilly Phase 3). Clinical trial enrollment is the only legal US access path. No 503A compounding path (not on Bulks List). Grey-market availability is essentially zero.
Pre-filled with this compound's published dose range: 2–12 mg once weekly (Phase 3 dose range: 2, 4, 8, 12 mg — no approved dose) · once weekly subcutaneous — investigational; no approved dosing exists
Draw volume exceeds 100 units (1 mL). Either reduce dose or split into multiple injections.
Calculator is a discussion tool. Verify reconstitution + dosing with a qualified provider. Stack is not a prescription source. Use sterile technique and inspect every vial.
How much a first cycle actually costs across the channels people use. Pick the protocol length you're considering — Stack multiplies the monthly band by cycle weeks. Same caveats apply: ranges are facts, quality varies, this is not legal advice.
Numbers reflect publicly-advertised price ranges, not vendor quotes. Insurance, prescription costs, and shipping aren't included. Channels marked unavailable are filtered out.
See pharmacies for this compound →Approximate monthly cost across the channels users actually consider — brand FDA-approved retail, US 503A compounding, Mexican pharmacies, MX farmacias magistrales, and the research-grey market. Stack lists ranges, not vendor names. Quality varies wildly across channels — see each band's note.
Not yet FDA-approved (Phase 3 trials ongoing as of April 2026).
As of 2026-04Research-grey only — no legitimate pharmacy access until FDA approval. Premium over Tirzepatide grey market reflects newer-compound scarcity.
As of 2026-04Distilled themes from named communities — Reddit threads, forums, creator commentary. Not direct quotes; not clinical evidence. Useful for calibrating expectations against what real self-experimenters report.
Cohort consensus: this is the 'next Zepbound' signal — post-Ozempic plateau users watching closely. Triple mechanism is the main hook. The knee OA data is drawing a different cohort (40-60s, higher BMI, joint-pain primary). Grey-market availability essentially zero as of May 2026 — clinical trial is the real path.
Next visit & citations
Running this compound? Log it in /history, then open Dr Passport before your visit. Methodology explains grades; the research dashboard sorts the full catalog with citations.