glp3.wiki

Protocol reference · 94 articles · primary sources only

Retatrutide (GLP-3): what the research says

Research on how retatrutide works, trial results, dosing, access, and nutrition. Independent information with links to primary sources.

Explore the researchRetatrutide calculatorRetatrutide dosage guide

What is GLP-3?

GLP-3 is not a real hormone or receptor. It is an informal consumer nickname for retatrutide (development code LY3437943), an investigational once-weekly injectable peptide from Eli Lilly. Retatrutide is a triple agonist: it activates GLP-1, GIP, and glucagon receptors at once. Peer-reviewed papers and FDA filings use “retatrutide” or “triple agonist,” not “GLP-3.”

People also search GLP-3 RT and GLP-3 reta — same drug. For the full mechanism and naming history, see What is retatrutide (GLP-3)? and GLP-1 vs GLP-2 vs GLP-3. Retatrutide is not FDA-approved as of July 2026.

INN / nameRetatrutide (investigational)
Dev codeLY3437943
ClassTriple agonist (GLP-1 + GIP + glucagon)
DeveloperEli Lilly
PhasePhase 3 (TRIUMPH / TRANSCEND programs)
Peak trial weight lossUp to ~24.2% at 48 wk (Phase 2 NEJM); ~28.3% at 80 wk (TRIUMPH-1 Phase 3 topline, May 2026)

Weight-loss figures are trial means under protocol conditions, not guaranteed individual outcomes. This is educational only — not medical advice.

What the trials showed

View statistics and sources →
−28.3%
Average weight loss, 12 mg at 80 weeks (TRIUMPH-1)
Eli Lilly and Company
2,339
Participants randomized in the pivotal Phase 3 trial (TRIUMPH-1)
ClinicalTrials.gov
45.3%
Participants losing ≥30% of body weight, 12 mg at 80 weeks
Eli Lilly and Company
−24.2%
Average weight loss, 12 mg at 48 weeks (Phase 2, NEJM 2023)
New England Journal of Medicine

Trial means for people who stayed on treatment. Not FDA-approved; not a prediction for any one person.

The questions people ask first

Is GLP-3 the same as retatrutide?
Yes. GLP-3, GLP-3 RT and reta are nicknames for retatrutide (LY3437943), Eli Lilly's investigational triple agonist. There is no GLP-3 hormone.What retatrutide is →
What does it do?
It activates the GLP-1, GIP and glucagon receptors at once. In the pivotal Phase 3 trial the 12 mg arm averaged 28.3% weight loss at 80 weeks, and 45.3% of those participants lost 30% or more.Results by dose →
Is it safe?
There is no label yet. In the trials the common effects were gastrointestinal, plus skin tingling at 12 mg, which is why the dose climbs slowly. The larger risk today is unverified vials sold online.Side effects and safety data →
How does it compare to tirzepatide?
Three receptors against two. Retatrutide averaged 28.3% at 80 weeks in TRIUMPH-1; tirzepatide 22.5% at 72 weeks in SURMOUNT-1. Different trials, so a head-to-head, TRIUMPH-5, is running.Retatrutide vs tirzepatide →
Can I get it?
Not by prescription. A clinical trial is one route; since 3 August 2026 a clinician can also apply to Lilly's expanded access program for a narrow group. Online vials are not a route.How to get retatrutide →
When will it be approved?
Lilly plans to file in the first quarter of 2027. A standard review puts a first decision in late 2027 or 2028.The approval timeline →

Choose a topic

  1. 01Research

    What is it, and what does it do?

    What it is, what the trials show, and how it affects your body.

  2. 02Trials

    Can I get it, and how?

    Clinical trials, expanded access, and their requirements.

  3. 03Calculator

    How do I calculate syringe units?

    Syringe units, trial dosing schedules, and injection technique.

  4. 04Nutrition

    What if I have trouble eating or feel unwell?

    Nutrition with a low appetite, side effects, and missed doses.

Every claim traces to a primary source
NEJMThe LancetJAMAFDAClinicalTrials.gov

Email guides

Choose an email series

Each series includes six emails and six printable guides.

The library

94 articles · every claim sourced

  1. 01RetatrutideRetatrutide topics: mechanism, trials, dosing, safety, and access.18
  2. 02CompareDrug comparisons grouped by treatment.22
  3. 03GLP-1 GuideDrug names, brands and receptor targets, with links to the evidence.8
  4. 04SafetySide-effect and safety topics — each article grounded in published trial data.8
  5. 05Trials & FDAFind recruiting studies, check eligibility and contact an official study site.4
  6. 06PeptidesUnderstand the different categories of peptide products and their evidence.4
  7. 07ConditionsIndications being studied — obesity, MASH, diabetes, sleep apnea, heart disease.5
  8. 08DrugsProfiles of every major weight loss drug we track.7
  9. 09StatisticsEvery published retatrutide efficacy and safety figure, with a primary source on each.
  10. 10Fact ChecksYouTube claims compared with clinical data.17
  11. 11GuidesFind an explanation or practical next step for your question.13
  12. 12GlossaryEvery term on the site, from agonist to titration, in plain words.