Retatrutide
WEIGHT MANAGEMENTQuick Specifications
| Vial Size | 5MG |
|---|---|
| BAC Water | 2ML |
| Amount Per Unit | 0.025MG PER UNIT |
| Recommended Dose | 0.5MG TO 4MG WEEKLY -- TITRATE SLOWLY |
| Frequency | ONCE PER WEEK |
| Injection Type | SUBCUTANEOUS |
| Timing | Weekly SubQ injection, same day each week. Titrate very slowly -- standard Phase 3 schedule: 0.5mg weeks 1-4, 1mg weeks 5-8, 2mg weeks 9-12, 4mg weeks 13+. Research protocols typically use 1-4mg maintenance. Never rush titration -- GI adverse effects are dose-escalation dependent. Fed or fasted. Use the interactive dose calculator for unit calculations. |
Research Overview
Retatrutide (LY3437943) -- widely called "Reta", "Ret", or "GLP-3" in the research and biohacking communities -- is a synthetic 39-amino acid triple receptor agonist developed by Eli Lilly that simultaneously activates GLP-1 (glucagon-like peptide-1), GIP (glucose-dependent insulinotropic polypeptide), and glucagon receptors. It is the most potent weight management compound in Phase 3 clinical research as of 2026. Phase 2 data showed 24.2% mean weight loss at 48 weeks with no plateau. TRIUMPH-4 Phase 3 data reported 26-29% mean weight loss at 48-68 weeks -- the highest ever recorded in a controlled pharmaceutical obesity trial -- with participants still actively losing weight at study end. The glucagon receptor component uniquely adds resting metabolic rate increase and hepatic fat oxidation on top of the appetite suppression driven by GLP-1/GIP agonism, producing additive weight loss that mono- and dual agonists cannot match. MASLD (metabolic dysfunction-associated steatotic liver disease) normalization occurred in approximately 93% of participants in sub-studies, with more than 80% reduction in liver fat content. Lean mass is largely preserved through GIP receptor co-activation. Gastrointestinal tolerability is comparable to tirzepatide and better than semaglutide at equivalent weight-loss-producing doses -- partly because GIP co-agonism buffers the GI side effects of GLP-1 agonism. Also known as GLP-3 or GLP-3 R in some research supply catalogs. As of May 2026, Retatrutide has not received FDA approval and remains a research compound. For research and educational purposes only.
How It Works
GLP-1 Receptor Agonism — Appetite Suppression
Retatrutide activates GLP-1 receptors in the hypothalamus and brainstem, triggering satiety signaling that reduces caloric intake. This is the foundational mechanism shared with semaglutide and tirzepatide. GLP-1 receptor agonism also enhances glucose-dependent insulin secretion and slows gastric emptying, contributing to sustained fullness after meals.
GIP Co-Agonism — Metabolic Efficiency and GI Tolerability
Simultaneous GIP receptor activation enhances insulin secretion through a complementary intracellular pathway that converges on overlapping cellular machinery in the pancreas, brain, and adipose tissue. Critically, GIP co-agonism improves GI tolerability of the GLP-1 component — explaining why tirzepatide and Retatrutide produce less nausea than semaglutide at weight-loss-equivalent doses.
Glucagon Receptor Agonism — Energy Expenditure
The third and distinguishing mechanism: glucagon receptor activation increases resting metabolic rate and drives hepatic fat oxidation. While glucagon alone raises blood glucose, at the doses used in Retatrutide this effect is buffered by concurrent GLP-1 and GIP-mediated insulin sensitization. The net result is an energy expenditure increase that operates independently of appetite suppression — producing additive weight loss that neither mono nor dual agonism can match.
Commonly Studied With
These peptides are frequently researched alongside Retatrutide (GLP-3 / Reta): 5mg due to complementary mechanisms:
For research-grade Retatrutide with third-party Certificate of Analysis documentation, Peptide Hub recommends Apollo Peptide Sciences. Apollo Peptide Sciences carries GLP-class compounds including Retatrutide in their weight management research catalog. Affiliate disclosure: we may earn a commission on purchases through this link.
Research references
The following PubMed resources are provided for educational reference. External links open in a new tab.
Retatrutide (GLP-3 / Reta): 5mg information on this page is for research and educational purposes only. This content is not FDA-approved, does not constitute medical advice, and should not be used to guide personal health decisions. Consult a qualified healthcare professional before using any research compound.
Dose Calculator
Enter your target dose to calculate the volume to draw.
Recommended dose: 0.5MG TO 4MG WEEKLY -- TITRATE SLOWLY