What it is. What the trials found. What nobody knows yet. And what a supplier can honestly tell you, which is less than most of them claim.
Retatrutide, in plain words
Mean weight loss at 48 weeks, phase 2
24.2%
One published trial. It describes people, not a vial.
Jastreboff et al, N Engl J Med 2023;389(6):514-526
Retatrutide is a lab-made copy of a hormone signal. It is not approved as a medicine anywhere in the world.
Both halves of that matter. Here is the rest, without the jargon.
Your gut makes hormones after you eat. They tell the rest of the body what to do next. Some of that signal reaches the pancreas. Some of it reaches the brain.
Drugs in this family copy those signals. They lock onto the same docking points the real hormones use. Those docking points are called receptors. Think of a receptor as a keyhole and the drug as a spare key.
The family splits by how many keyholes a drug fits.
| Drug | Keyholes it fits | How many |
|---|---|---|
| Semaglutide | GLP-1 | 1 |
| Tirzepatide | GLP-1 and GIP | 2 |
| Retatrutide | GLP-1, GIP and glucagon | 3 |
Retatrutide fits three. That is the whole reason people talk about it.
The third one, glucagon, is the new part. The first two mostly deal with appetite and blood sugar. The glucagon keyhole is tied to how much energy the body burns and how the liver handles fat. So on paper it works on a different lever as well.
On paper is doing a lot of work in that sentence. Whether it actually makes a real difference is the thing still being tested.
No medicines regulator anywhere has approved retatrutide. Not the FDA. Not the European Medicines Agency. Nowhere.
It is still in trials. Eli Lilly, the company that made it, is running those trials now. That is what "investigational" means. It is being studied, and the studying is not finished.
Here is a simple way to see how new it still is. Search the main medical research database and you get about 178 papers on retatrutide. Search tirzepatide and you get about 2,477. Roughly fourteen times as many.
Tirzepatide is a finished medicine. Retatrutide is a work in progress. Both facts are neutral. But they mean far less is known about one than the other, and anybody who talks about them as if they were the same thing is skipping that.
New England Journal of Medicine / Phase 2
The main published human study was a Phase 2 trial. It ran for 48 weeks with 338 adults. It was published in the New England Journal of Medicine and paid for by Eli Lilly.
Phase 3 has since started reporting. The larger TRIUMPH programme is under way, and reviews published in 2026 now refer to Phase 3 TRIUMPH data while noting the compound is still awaiting cardiovascular outcome data. Detailed trial papers are not out yet, so the numbers below remain the fullest published human results. Treat headline figures circulating online as topline announcements rather than published trials.
Phase 2 is the middle stage. It tests whether a dose does anything and roughly what the side effects look like. It is not the final stage, and it does not settle safety.
People got a weekly injection. After 48 weeks, average weight change was:
| Weekly dose in the trial | Average weight change at 48 weeks |
|---|---|
| 1 mg | -8.7% |
| 4 mg | -17.1% |
| 8 mg | -22.8% |
| 12 mg | -24.2% |
| Placebo (no drug) | -2.1% |
Those are the numbers everyone quotes. They are real, and they came from that trial.
The same paper reports the downsides. They belong here too.
Most side effects were stomach and gut problems. They got worse at higher doses. Most were mild or moderate. Starting on a lower dose made them less bad.
And this one: heart rate went up, more at higher doses. It peaked around 24 weeks, then came back down. That is the authors' own reporting, not a critic's.
A striking Phase 2 result is a reason to run a bigger trial. It is not proof of anything. Drugs look good at this stage and then fail at the next stage all the time. That is why the next stage exists.
NCT06662383 / November 2026
This is the question everyone argues about online. It has an answer coming, and it is not here yet.
There is a trial running right now that puts the two head to head. It is Phase 3. It has
800 people in it. It is double-blind, so neither the patients nor the doctors know who got
which drug. Its registry code is NCT06662383.
It finishes gathering data in November 2026. Results come out some months after that.
So if someone tells you today which one wins, they are answering a question the actual study has not finished asking. Everything before then is guesswork stitched together from two different trials with different people in them.
Janoshik / batch RT6423CP / 25 May 2026
This is the part that matters most when you are buying something.
Those trial results came from a specific setup. Drug made by the company that invented it. Exact doses set by a protocol. Patients screened first to check they were suitable. Doctors watching. Side effects written down and reviewed.
Take any one of those away and you no longer have the trial. You have something else.
A vial has none of them. No protocol. No screening. No supervision. No one recording what happens. So a trial percentage does not describe a bottle on a shelf, and a supplier quoting one at you is quoting somebody else's homework.
Not that it works. Not that it is safe. Those come from trials, and no supplier runs trials.
What can be proved is narrow and checkable: that the powder is the compound on the label, at the purity stated, in the amount stated, from a batch you can trace.
A published example looks like this: outside lab Janoshik, batch RT6423CP,
purity 99.744 percent, 22.43 mg in a vial labelled 20mg, analysed 25 May 2026. The report
carries a key you check with the laboratory yourself.
Every figure above sits on a published certificate with the laboratory named and the batch printed, before anyone asks you for money. Of twenty sellers we probed in September 2026, twelve publish no certificate page at all.
Every seller looks the same on the good day. Four things decide what happens on the bad one, and all four are published before you order if you go and read them.
Read the seller's own published pages, not their marketing, and none of these terms were written by us.
The plain page on retatrutide, plus the four things to check on a certificate before you buy any of it, from anyone.
You are on the list.
The sheet comes by email, as one page you can print.
It follows once our list is live, and nothing else is sent. We do not sell peptides and we are not going to email you about any.
One email with the sheet. Unsubscribe in one click. We do not share addresses.
Before you go
One sheet, in plain language, that you can run on any seller in any country. One column filled in from a published certificate, and one left empty for the seller you already have open.
You are on the list.
The sheet comes by email, as one page you can print.
Nothing else follows it. We do not sell peptides and we are not going to email you about any.
One email with the sheet. Unsubscribe in one click. We do not share addresses.