Retatrutide is an investigational once-weekly injectable drug developed by Eli Lilly and Company. It belongs to a new class of obesity medications that work by activating three distinct hormone receptors simultaneously — a mechanism that sets it apart from every weight-loss drug currently on the market. Although it has not yet received FDA approval and no brand name has been announced, retatrutide has already produced the highest mean weight loss ever recorded in a Phase 3 obesity trial: 28.7% of body weight over 68 weeks in the TRIUMPH-4 study.
For context, semaglutide (Wegovy) produced roughly 15% mean weight loss over 68 weeks in the STEP-1 trial, and tirzepatide (Zepbound) produced 20.9% at its highest dose over 72 weeks in SURMOUNT-1. Retatrutide's TRIUMPH-4 results represent a meaningful step beyond both — and the scientific community is paying close attention.
The term "GLP-3" — sometimes written as GLP3 or glp 3 — has spread rapidly through patient forums, social media, and health news outlets. It is important to understand what this label means and, equally, what it does not mean.
GLP-3 is not an official pharmacological classification. There is no hormone in the human body formally designated GLP-3 in the way GLP-1 (glucagon-like peptide-1) is. The nickname emerged colloquially because retatrutide goes beyond GLP-1 and GLP-1/GIP dual agonism — it adds a third receptor target, glucagon — making it feel like the "next generation" after GLP-1 and GLP-2 analogs. Consumer media latched onto "GLP-3" as shorthand, and the term has taken on a life of its own in patient communities.
Retatrutide is not the same molecule as GLP-1. Its International Nonproprietary Name (INN) is simply retatrutide. Eli Lilly has not announced a commercial brand name as of April 2026. When reading about "GLP-3" online, readers should understand they are almost certainly encountering informal language for retatrutide specifically — not a separate drug class or a distinct hormone.
This question appears frequently in search engines, and the answer is straightforward: no oral (pill) form of retatrutide is currently in development or approved. Retatrutide in all clinical trials to date — including the Phase 2 obesity study published in the New England Journal of Medicine in 2023 and the Phase 3 TRIUMPH-4 trial — is administered as a once-weekly subcutaneous injection, similar to how semaglutide and tirzepatide are delivered.
There is no peer-reviewed evidence, no Eli Lilly pipeline disclosure, and no regulatory filing indicating that a GLP-3 pill or oral retatrutide formulation is in active clinical development. Anyone encountering references to "GLP-3 pills" or "GLP3 pills" online should treat those claims with significant skepticism.
The term triple agonist refers to retatrutide's ability to activate three hormone receptors at once. Most weight-loss medications target only one or two of these pathways. Here is how retatrutide compares:
| Drug | GLP-1 Receptor | GIP Receptor | Glucagon Receptor | Approx. Mean Weight Loss (Phase 3) |
|---|---|---|---|---|
| Semaglutide (Wegovy) | ✓ | — | — | ~15% (68 weeks, STEP-1) |
| Tirzepatide (Zepbound) | ✓ | ✓ | — | ~20.9% at 15mg (SURMOUNT-1) |
| Retatrutide (investigational) | ✓ | ✓ | ✓ | 28.7% at 12mg (68 weeks, TRIUMPH-4) |
Each receptor plays a distinct role. GLP-1 receptor activation slows gastric emptying, reduces appetite, and dampens what patient communities commonly call food noise — that persistent mental preoccupation with eating. GIP receptor activation appears to enhance the metabolic and tolerability effects of GLP-1 agonism. The glucagon receptor component is particularly notable: glucagon stimulates energy expenditure in the liver and promotes fat breakdown, which may explain why retatrutide produces weight loss that appears meaningfully greater than dual agonists alone.
Retatrutide is sometimes called a GGG tri-agonist — shorthand for GLP-1/GIP/Glucagon — to reflect all three receptor targets in a single molecule. Rather than combining three separate drugs, Eli Lilly's chemists engineered a single peptide capable of engaging all three receptors with appropriate potency at each.
In the Phase 2 trial published in the NEJM, participants receiving the 8mg dose achieved a mean weight loss of approximately 22.8% over 48 weeks, with 100% of participants in that arm losing at least 5% of body weight and up to 70% achieving weight loss of 20% or more. Cardiometabolic benefits were also striking: triglycerides fell by as much as 39% and LDL cholesterol dropped approximately 16–17% at 24 weeks in higher-dose groups. These metabolic effects likely reflect the combined activity of all three receptor pathways, including glucagon's direct influence on hepatic lipid metabolism.
The most common side effects were gastrointestinal — nausea, diarrhea, and vomiting — consistent with the GLP-1 class and most pronounced during dose titration. A notable finding unique to retatrutide is dysesthesia (an unusual skin sensation), which occurred in 20.9% of participants at the 12mg dose in TRIUMPH-4, compared with 0.7% on placebo. This side effect warrants monitoring and is an important part of informed patient education.
Retatrutide is being developed exclusively by Eli Lilly and Company, the same pharmaceutical manufacturer behind tirzepatide. The compound's study identifier is LY3437943. Phase 2 results were published in the New England Journal of Medicine in 2023 by Jastreboff and colleagues. The Phase 3 TRIUMPH-4 trial reported results via press release in December 2025, with peer-reviewed publication pending as of April 2026.
As of April 2026, Eli Lilly has not filed a New Drug Application (NDA) with the FDA, and no approval timeline has been publicly confirmed. Retatrutide remains an investigational drug — meaning it is not available by prescription outside of clinical trials.
Retatrutide may represent a meaningful advance in obesity medicine, and the landscape is evolving quickly. glp3md is a retatrutide information and waitlist platform designed to keep patients informed as the regulatory process unfolds. Joining the waitlist at https://www.glp3md.com is a way to stay up to date on trial developments, approval timelines, and emerging clinical data — not a guarantee of access to any medication or treatment. Because retatrutide is not yet FDA-approved, no promises can be made about medication availability, prescriptions, or participation in any treatment program. The waitlist is for informational purposes only. That said, being early and informed is always an advantage when a new therapy reaches the clinic.
Join the waitlist for priority access to a prescribing physician when retatrutide receives FDA approval.
Join the WaitlistThis article is for educational purposes only and does not constitute medical advice. Retatrutide is an investigational drug and is not FDA approved as of publication. Clinical data referenced is from publicly available trial publications. Consult a qualified healthcare provider before making any treatment decisions.