Retatrutide: uses, evidence and status

compound file

The answer, first. A once-weekly triple agonist of GLP-1, GIP and glucagon receptors, developed by Eli Lilly, first published in humans in 2022 and approved nowhere. The strongest evidence is for weight reduction in obesity, graded B — one well-powered human trial.

Phase 2: 24.2% lost at 12 mg vs 2.1% on placebo at 48 weeks, and the curves had not plateaued ¹. The strongest published weight-loss result. Still mid-stage, approved nowhere ¹⁷.

What it is used for

Every use graded on its own evidence, not the compound as a whole. 3 outcomes, ranked by what the human record supports.

#outcome · human · animal · gradewhat the best evidence actually shows

01Weight reduction in obesityphase 2, n=338, 48 weeks · superseded by human trialsgrade BPhase 2: 24.2% lost at 12 mg vs 2.1% on placebo at 48 weeks, and the curves had not plateaued ¹. The strongest published weight-loss result. Still mid-stage, approved nowhere ¹⁷.

02Type 2 diabetes glycemic controlphase 2, n=281, 36 weeks · superseded by human trialsgrade BPhase 2: HbA1c fell 2.02 points at the top dose vs 0.01 on placebo at 24 weeks, holding at 36 ². Weight fell up to 16.9% ². No phase 3 readout yet.

03Liver fat in MASLDsubstudy, n=98 · superseded by human trialsgrade CSubstudy: liver fat fell 82.4% at 12 mg vs a 0.3% rise on placebo at 24 weeks ³. 86% reached normal liver fat ³. A 98-person substudy, not an outcomes trial.

gradewhat it means

ARegulatory approval, or multiple adequately-powered trials agreeing with each other

BAt least one well-powered human randomised trial, with the direction replicated

CSmall or open-label human trials only

DAnimal or mechanism data only, with no controlled human outcome

EA claim the human trials have already killed

How it works

The proposed mechanism, in three steps. A mechanism is a reason to run a trial, never a substitute for one.

1targetOne peptide, three receptors: GLP-1, GIP and glucagon, engineered on the GIP backbone for once-weekly dosing ⁴.

2signalThe GLP-1 and GIP arms work the intake side, appetite and gastric emptying. The glucagon arm adds hepatic action and energy expenditure ¹³.

3effectBody weight fell 24.2% at 48 weeks on 12 mg ¹. Liver fat normalized in 86% of MASLD participants at 24 weeks ³.

What it does not do

Claims the current record does not support. Worth knowing before you set expectations.

not supported by the evidence

Approved successor to tirzepatide. Approved nowhere. Phase 3 TRIUMPH has posted no results. No regulator has reviewed it ⁷.
Proven superiority over approved incretins. No head-to-head has published. Its phase 2 number against their phase 3 numbers is indicative, not a ranking ¹⁵⁶.
Established long-term safety. A 338-person, 48-week trial cannot find rare harms. Heart rate rose dose-dependently, peaking at 24 weeks ¹.

How it is used

What published protocols administered, and what the community reports doing. Descriptive on both counts, and never a recommendation.

routeOnce-weekly subcutaneous injection in the trials ¹. No approved product or route exists.

formatNo pharmaceutical product anywhere. Sold only as gray-market lyophilized research vials.

published dosesNo label exists. Phase 2 randomized 1, 4, 8 and 12 mg weekly for 48 weeks ¹. Higher arms escalated from 2 or 4 mg starts, and the 2 mg start eased gastrointestinal events ¹. The diabetes trial ran 0.5 to 12 mg ².

human pharmacokineticsHalf-life approximately 6 days in phase 1, dose-proportional, supporting weekly dosing ⁴.

reported conventionsAs reported on r/retatrutide and group-buy threads, 2024-2026: weekly injections, 0.5 to 2 mg starts, monthly steps toward 4 to 8 mg. A minority run 12 mg. Resting heart rate is tracked alongside. Convention, not guidance.

commonly paired withCagrilintide

This site does not publish protocols to follow. The doses above are what studies administered or what users report, stated as facts about the literature and the market. How protocols are structured, mixing and storage and the reconstitution calculator cover the arithmetic.

What to expect

Where a trial measured it, the trial. Where only the community reports it, that is said out loud.

onsetPhase 2 measured 7.2 to 17.5% lost across doses by week 24, and 24.2% at week 48 on 12 mg ¹. The curve was still falling at trial end ¹. Nothing is measured beyond 48 weeks.

most common reportAs reported: early appetite suppression, steady weekly loss, and a raised resting heart rate as the recurring self-measurement.

adverse effectsPhase 2: gastrointestinal events most common, dose-related, mostly mild to moderate, partly mitigated by 2 mg starts ¹. Dose-dependent heart-rate increases peaked at 24 weeks, declining after ¹. No large-scale or long-term safety data exists.

the stop signalNo label defines one. The trial managed intolerance through slower escalation ¹. As reported: sustained heart-rate elevation or unrelenting nausea is treated as the stop signal.

Approval and status

What regulators and sport bodies have actually said, separately from what the evidence shows.

approvalNone. Investigational. Phase 3 TRIUMPH is underway. Approved nowhere, for anything, by any regulator.

FDANot reviewed by FDA for any use. Lilly states availability only through its trials. Every vial sold sits outside the approval framework, unverified by any regulator.

sport [WADA]Not named on the WADA Prohibited List. Incretin agonists are not banned.

sold asresearch chemical

Covered in depth

These reports grade Retatrutide at length and carry their own verified reference lists.

Retatrutide: best data, unproven

The phase 2 numbers everyone quotes, what the phase 3 program still has to prove, and where the hype outruns the data.

Check the vial

The grade above describes a molecule studied under controlled conditions. It says nothing about the powder in a particular vial.

That gap is the one part of this market a reader can actually close. How to read a certificate of analysis covers the five measures in five minutes, and the 2026 audit grades vendors on the documents they publish against a rubric printed in full.

Questions we get

What is Retatrutide used for?

Nothing, in the approved sense. No regulator has cleared it for any use. In trials it is being tested for obesity, type 2 diabetes, liver disease, osteoarthritis pain and cardiovascular and kidney outcomes ¹²³⁷.

The phase 2 obesity result, 24.2% lost at 48 weeks, is the strongest published for any weight-loss drug ¹. It is also a 338-person, mid-stage number ¹. The gray market sells against that gap.

How is Retatrutide used?

There is no label to describe. The phase 2 trial injected 1 to 12 mg weekly for 48 weeks, the higher arms escalating from 2 or 4 mg starts ¹.

As reported on r/retatrutide, gray-market vials are reconstituted and dosed weekly, 0.5 to 2 mg starts stepping toward 4 to 8 mg. Descriptive only. Convention, not guidance.

How long does Retatrutide take to work?

In phase 2, every dose separated from placebo early ¹. Means reached 7.2 to 17.5% lost by week 24 and 24.2% at week 48 on 12 mg, without plateauing ¹. Nothing past 48 weeks is measured. That is exactly what TRIUMPH exists to answer: durability, rare harms, cardiovascular outcomes ⁷.

Is Retatrutide an approved drug?

No. Retatrutide is sold as a research chemical, not as an approved medicine. On our index it is graded phase 3 on clinical evidence and very high on community adoption, and those two are rated separately on purpose.

Phase 3 also means the odds are unsettled: published estimates put the chance of approval from phase 2 well under half across therapeutic areas.

Is Retatrutide stronger than Tirzepatide or Semaglutide?

Its phase 2 number is larger than their phase 3 numbers. 24.2% at 48 weeks against tirzepatide's 20.9% over 72 ⁵, and semaglutide's 14.9% over 68 ⁶. Different trials, durations and populations. Indicative, not a ranking. No head-to-head has published. Lilly is running one against tirzepatide now ⁷.

References

Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med. 2023. PMID 37366315
Rosenstock J, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial. Lancet. 2023. PMID 37385280
Sanyal AJ, et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nat Med. 2024. PMID 38858523
Urva S, et al. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b trial. Lancet. 2022. PMID 36354040
Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity [SURMOUNT-1]. N Engl J Med. 2022. PMID 35658024
Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity [STEP 1]. N Engl J Med. 2021. PMID 33567185
Eli Lilly. TRIUMPH phase 3 program, retatrutide. ClinicalTrials.gov registrations. 2023-2026. clinicaltrials.gov

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