The triple agonist (GLP-1 + GIP + glucagon) in Phase 3 trials — showing the largest weight-loss results yet seen, with early data pointing to ~24% body-weight reduction.
Retatrutide (LY3437943) is a triple agonist that activates three metabolic receptors simultaneously: GLP-1, GIP, and glucagon. Developed by Eli Lilly, it’s currently in Phase 3 trials for obesity, type 2 diabetes, NAFLD, and obstructive sleep apnea.
The addition of glucagon receptor agonism is what differentiates it from tirzepatide. Glucagon increases energy expenditure and fat oxidation, which is why Phase 2 results showed ~24% body-weight loss at 48 weeks — the largest number seen in any weight-loss drug trial to date.
Not yet FDA approved (Phase 3 as of 2026). Not WADA prohibited. Available as a research chemical only.
Same as semaglutide: appetite suppression, delayed gastric emptying, glucose-dependent insulin release.
Same as tirzepatide: enhances fat metabolism in adipose tissue and partially offsets GLP-1 GI side effects.
Glucagon increases resting energy expenditure (metabolic rate) and promotes hepatic fat oxidation. It’s what lets retatrutide push weight loss beyond the GLP-1/GIP ceiling — the body is burning more energy even at rest.
GLP-1 suppresses intake, GIP redirects fat metabolism, glucagon increases expenditure. Combined, weight loss is deeper than any single or dual agonist can achieve.
| Benefit | Evidence |
|---|---|
| Weight loss | Phase 2: ~24% body-weight loss at 48 weeks on 12 mg; weight still declining at trial end (no plateau) |
| HbA1c reduction | Phase 2 T2D: HbA1c drops up to 2.0% at 12 mg |
| Liver fat (NAFLD/MASH) | ~80% reduction in liver fat content at higher doses |
| Resting energy expenditure | Increased vs baseline — a mechanism other GLP-1s lack |
| Lipid profile | Favorable changes in triglycerides and LDL |
Phase 3 program (TRIUMPH) is ongoing; FDA submission expected 2026–2027.
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Start Tracking FreeSlow titration is critical — retatrutide’s GI side effects can be intense at dose jumps.
| Weeks | Weekly Dose |
|---|---|
| 1–4 | 2 mg |
| 5–8 | 4 mg |
| 9–12 | 6 mg |
| 13–16 | 8 mg |
| 17–20 | 10 mg |
| 21+ | 12 mg (max studied) |
Note on the studied schedule: PMID 37366315 (Phase 2) actually used starting doses of 2 mg or 4 mg titrating to target maintenance doses of 4 mg, 8 mg, or 12 mg — 6 mg and 10 mg were not studied as maintenance arms. The uniform 2 mg step-up table above is a community interpolation for smoother tolerability; the trial-validated targets are 4, 8, and 12 mg. Many users settle at 4–8 mg once appetite and weight trajectory are where they want — max dose isn’t required.
10 mg vial + 2 mL BAC water = 5 mg/mL
| Dose | Volume | Syringe Units |
|---|---|---|
| 2 mg | 0.40 mL | 40 units |
| 4 mg | 0.80 mL | 80 units |
| 6 mg | 1.20 mL | 120 units (split if needed) |
| 8 mg | 1.60 mL | 160 units |
For higher doses (10–12 mg) reconstitute with less water (1 mL → 10 mg/mL) to keep injection volumes practical.
Use our free peptide calculator to figure out your reconstitution volume, draw amount, and syringe units.
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Retatrutide’s side effect profile is similar to other GLP-1/GIPs but with some additional glucagon-related considerations.
Human long-term safety data are limited. Not recommended for use outside of trial settings without medical supervision.
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Start Tracking FreeDisclaimer: This guide is for educational and informational purposes only and is not intended as medical advice, diagnosis, or treatment. The compounds discussed are not FDA approved for human use. Always consult a qualified healthcare provider before starting any new supplement or peptide protocol. StackTrax does not sell peptides or supplements directly — purchase links go to third-party vendors. StackTrax is not responsible for the products, quality, or business practices of any third-party vendor. This page contains affiliate links — StackTrax may earn a commission on purchases at no extra cost to you.
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