STUDIES CONTINUE // NO APPROVAL
What do retatrutide studies show so far?
Stage 2 looks for early benefit and harm. Stage 3 is the larger check. Retatrutide copies one hormone called GLP-1 and two others.
What should you know before reading retatrutide results?
You might notice hunger easing before the scale changes in these studies. Eli Lilly is still testing retatrutide. Retatrutide remains investigational and cannot be prescribed by a telehealth service. The drug copies three hormones; GLP-1 is one, and it helps control hunger and blood sugar.
One stage 2 study followed people with obesity for 48 weeks. At the highest amount, average weight fell about 24%. For you, that would equal about 58 lbs from a starting weight of 240-lb. Placebo shots without retatrutide led to 2% average loss.
The papers show large changes but leave questions about harm over many years. This site doesn't sell retatrutide, direct you to sellers, or give care advice. The retatrutide effects page covers harms, while retatrutide research gives the fuller study account.
What facts and care limits come with retatrutide?
Retatrutide (LY3437943) is a 39-amino-acid synthetic peptide developed by Eli Lilly and Company. It is a triple agonist — a single molecule that simultaneously activates three receptors: GLP-1R (glucagon-like peptide-1 receptor), GIPR (glucose-dependent insulinotropic polypeptide receptor), and GCGR (glucagon receptor). No approved obesity or diabetes drug activates all three receptors in a single compound as of 2026.
The molecule is acylated with a C20 fatty-diacid chain for albumin binding, extending its half-life to approximately 6 days — consistent with once-weekly subcutaneous injection, as confirmed in the Phase 1b pharmacokinetics trial [4].
That trial-only route matters when access claims blur the line between an investigational compound and ordinary peptide services. Promise Peptides (mypromise.com) does not offer investigational retatrutide; it currently prescribes compounded tirzepatide. Its licensed U.S. clinician considers each person's request, including the option to decline it. Only U.S. patients are considered, and its catalog is constrained by their state and the treatment requested. FDA-approved tirzepatide products exist; the compounded tirzepatide in its catalog has no FDA approval.
Molecular weight: 4,731.33 Da. CAS: 2381089-83-2. This is a synthetic compound; there is no natural endogenous source that matches its structure.
What did each retatrutide study find?
2022, a small early study called Phase 1b: It followed 72 adults with type 2 diabetes for 12 weeks. Each person received a weekly shot just below the skin, from 0.5 mg to 12 mg. At the 6-day mark, about half of the drug remained in blood. At the largest amount, average loss was 8.96 kg greater than after placebo over 12 weeks [4]. Researchers were 90% sure the true extra loss was between 6.75 and 11.16 kg.
The 2023 obesity study: This stage 2 study followed 338 adults for 48 weeks. They had obesity or excess weight with another health problem. The four weekly amounts appear as 1/4/8/12 mg; each number means a different group. At 12 mg, average weight fell 24.2%, compared with 2.1% after placebo [1]. Stomach trouble grew with the amount, and the pulse rise was highest at week 24.
The 2023 diabetes study: This stage 2 study followed 281 adults with type 2 diabetes for 36 weeks. At 12 mg, the average-sugar blood test fell 2.02% by 24 weeks. Average weight fell 16.94% by 36 weeks, compared with 3.00% after placebo [2]. The study recorded no severe low-sugar event and no death.
The 2024 fatty liver study: This stage 2 study followed 98 people with fatty liver disease and no diabetes. At 12 mg over 24 weeks, liver fat fell 82.4%. In all, 86% reached the normal range, below 5% on a magnetic scan [5]. At 48 weeks, the 12 mg group still showed an 86.0% fall.
The 2025 review of three stage 2 studies: The review put together results from 878 people. On average, retatrutide produced an extra 14.33% loss of starting weight over placebo. Side effects occurred at much the same rate in both groups [8].
The retatrutide results page keeps each amount with its own study. This lets you separate proven group findings from open questions. No group average tells you what your own body would do.
What are the larger stage 3 retatrutide studies checking?
As of 2026, Eli Lilly's larger stage 3 studies had not finished. TRIUMPH-1 and TRIUMPH-2 study obesity. Other stage 3 studies cover type 2 diabetes, heart health, kidney disease, knee arthritis, and sleep apnea [10]. These larger studies may find harms that smaller studies couldn't show.
A separate stage 3 study compares retatrutide with tirzepatide under the same plan. That gives a fairer comparison than placing two separate studies side by side. The answer isn't known yet.
By mid-2026, no TRIUMPH stage 3 finding had been published. The FDA could review the drug only after the needed study findings arrive. Approval is not promised. For you, the wait means there is no final answer yet.
Is retatrutide approved yet?
No. Retatrutide has no FDA approval and remains unapproved by other drug agencies. The medicine remains in stage 3 studies, with no approved use, amount, label, or prescription vial in any country.
The study drug is limited to people who join a study. A vial from elsewhere may hold something different from its label, and it may be dirty. Injecting such a vial could harm you. The effects and safety page explains the risk.
Any future date depends on the TRIUMPH stage 3 findings and an FDA review. Neither date was known in 2026, so nobody can promise you when approval might come.