⚖️ Weight Management

Retatrutide

Also called LY3437943, triple agonist, triple G, retra

The one that works on three hormones at once

Retatrutide is an experimental weekly weight-loss injection from Eli Lilly. It copies three hormones your body already makes, two that tell your brain you are full and one that raises the energy you burn at rest. In its main trial people lost an average of 24.2% of their body weight over 48 weeks. It is not approved yet.

Retatrutide is a weekly injection being tested for weight loss. Most drugs in this family copy one or two of your gut hormones to blunt appetite. Retatrutide copies three, and the third one also nudges up the energy you burn while resting, so weight comes off through burning a little more as well as eating a little less. In its main trial people lost an average of 24.2% of their body weight in 48 weeks, and the weight was still dropping when the trial ended. It is still being tested and is not approved anywhere.

Half-life: About 6 days
Route studied: Subcutaneous injection (trials)
Status: Investigational; not approved anywhere

Emerging Evidence

Human trials published, with more underway

160 papers · 7 clinical trials

See the research

What Retatrutide has been studied for

The reasons people look it up, roughly in order of how often, and what research exists for each. Interest in a use is not evidence that it works; the evidence is stated under each one.

Weight loss (investigational): Studied in a phase 2 trial of 338 adults with obesity (Jastreboff et al., 2023): weekly injections for 48 weeks, with the 12 mg group losing an adjusted average of 24.2% of body weight. The phase 3 trials that decide approval have not reported.
Fatty liver: The glucagon component acts directly on the liver, and liver fat fell in phase 2 participants who had it measured. Whether that holds in larger trials is not yet known.

Mechanism of Action

How Retatrutide works

Your gut releases hormones after you eat. They are the reason a meal eventually makes you feel done. Retatrutide copies three of them at once.

The fullness signal tells your brain you have eaten enough and slows how fast your stomach empties, so meals stay satisfying for longer. This is the same signal Ozempic uses.
The insulin-sensitivity signal helps your body handle sugar and fat more efficiently, and adds a second, separate nudge toward feeling full. This is what Mounjaro added on top.
The energy-burning signal is what makes retatrutide different. It raises the amount of energy you burn at rest and pushes your liver to use up its stored fat. Nothing else in this class does it.

The practical difference: the other drugs mostly work by making you eat less. Retatrutide does that too, and then also raises what you burn. That is why its trial numbers came in higher, and why the liver-fat results stood out.

What the Retatrutide trials used, and what each arm produced

Retatrutide is not approved. No regulator has cleared it, so there is no established dose and nothing below is a recommendation. It is a record of what a published trial ran.

Retatrutide is not approved, so there is no prescribed dose. What exists is the phase 2 trial: 338 adults with obesity, randomised to placebo or one of several weekly doses, most of them reached through a 12-week step-up. Here is what each group was given and the average weight change recorded at 48 weeks.

Retatrutide trial doses and the average body-weight change at 48 weeks each one produced
Dose	How it was given	Average body-weight change at 48 weeks
Placebo	Weekly injection	−2.1%
1 mg	Weekly, no step-up	−8.7%
4 mg	Weekly, stepped up over 12 weeksTwo groups reached 4 mg by different routes, one starting at 2 mg and one at 4 mg. The trial reports them as one figure.	−17.1%
8 mg	Weekly, stepped up over 12 weeksTwo groups reached 8 mg by different routes, one starting at 2 mg and one at 4 mg. The trial reports them as one figure.	−22.8%
12 mg	Weekly, stepped up over 12 weeks from 2 mgPeople in this group were still losing weight when the trial stopped, so nobody knows where it would have levelled off.	−24.2%

Least-squares mean change in body weight from the start of the trial to 48 weeks. This is an adjusted average, not a raw one.

Source: Jastreboff et al., Triple-Hormone-Receptor Agonist Retatrutide for Obesity, a Phase 2 Trial, New England Journal of Medicine, 2023. 338 people, randomised across seven groups.

These are group results from the study named above. They describe what happened in that trial, not a dose for anyone. This is not medical advice, and decisions about any medicine belong with a licensed clinician.

Retatrutide side effects: what studies reported

In the phase 2 trial, most reported side effects were stomach-related, and most occurred during the dose step-up period rather than afterwards.

Most commonly reported

Nausea
Diarrhoea
Vomiting
Constipation

Worth knowing about

Heart rate went up on higher doses. It peaked around the 24-week mark and then came back down over the rest of the trial.

Not yet answered

What happens past 48 weeks, and what happens if you stop
How it behaves in people who were not part of this trial group

Dose-related findings. In the trial, reports were more frequent in the higher-dose groups and fell after the step-up period.

Source: Jastreboff et al., New England Journal of Medicine, 2023. The larger Phase 3 trials have not reported yet, so the long-term picture is still being filled in. This is a summary of published findings, not a complete safety profile and not medical advice. Questions about Retatrutide belong with a licensed clinician who knows your history.

Your Genetics & Retatrutide

The genes involved in how Retatrutide works

Retatrutide works through the receptors these genes build, and the genes vary from person to person. Researchers have linked some of that variation to differences in how people respond. A DNA report tells you which versions you carry.

GCGRThe energy-burning signal

This is the gene for the receptor that handles retatrutide's third hormone, the one that raises what you burn at rest. It is the part of retatrutide that no other drug in this class has, so this gene is worth looking at here and is beside the point for Ozempic or Mounjaro. Studied for its association with how strongly that signal comes through.

Chromosome 19The insulin-sensitivity signal

GIPR · ••

The Glu354Gln variant is associated with differences in how this receptor is made and how strongly it responds. Retatrutide shares this signal with Mounjaro, so it relates to part of the appetite and blood-sugar effect rather than the whole thing.

Chromosome 6The fullness signal

GLP1R · ••

The Gly168Ser variant sits in the receptor for the main fullness hormone and has been associated with differences in how much weight people lose on drugs in this family. It relates to the part of retatrutide that overlaps with Ozempic.

Chromosome 10Blood-sugar control

TCF7L2 · ••

The most common inherited variant linked to type 2 diabetes risk. People carrying the T version tend to release less insulin after eating. It is included because it relates to the blood-sugar side of how these drugs behave, not to how much weight you lose.

The dots after each gene are where your own result goes. Your report fills them in with the two letters you carry at that position.

Which of these variants do you carry?

Your report reads the DNA file you already have against this research.

Read my DNA, $99

Access

Access and legal status

Retatrutide: Investigational; not approved anywhere. Decisions about any prescription medicine belong to a prescriber. We don't link to any seller, and nothing on this page is a recommendation to obtain or use it.

Your DNA and Retatrutide: see which of the variants studied alongside it you carry, and what that research does and does not show. Read my DNA, $99 →

Educational information only, not medical advice. Most peptides are not FDA-approved. Do not start, stop or change any medication or peptide because of this page; talk to a licensed clinician.

Worth knowing about Retatrutide

Interactions and situations where there is a specific reason to be careful. Where the honest answer is that nobody has studied something, it says so and says what that leaves open.

Investigational, with no lawful consumer source: It is still in phase 3 trials and is not approved anywhere, so there is no lawful way for a consumer to obtain it in the US. Products sold online under the name are not the compound Eli Lilly is testing, and their content is unknown.
Heart rate goes up: The glucagon component raises energy expenditure, and heart rate rose with it in the phase 2 trial: it climbed, peaked around week 24, then came back down. Relevant for anyone with a heart condition.
Side effects clustered in the step-up period: In the phase 2 trial, most groups reached their final dose through a 12-week step-up, and stomach side effects were most frequent during that period.

The evidence behind Retatrutide

Worth comparing against the research peptides. Retatrutide has fewer papers than BPC-157 does, 160 against 224, and seven of them are indexed as clinical trials where BPC-157 has none. A bigger pile of papers is not more evidence; what matters is whether any of it was a trial in people.

The literature, counted

160Papers indexed 107Preclinical 100Tagged human 7Clinical trials

Counted in PubMed on 2 August 2026 for retatrutide. Every figure links to the search that produced it, so you can re-run it. “Tagged human” is not the same as a human trial: that tag also covers work on human cells and reviews discussing people, which is why the trial count is given separately.

Studied in people

2 of 2The only kind that directly answers whether it works in humans.

Last updated 2 August 2026 · literature counts verified against PubMed on 2 August 2026

Frequently Asked Questions

Can I get retatrutide?

Not legitimately, no. It has not been approved by any regulator, which means no pharmacy can fill a prescription for it. The 24.2% figure that gets quoted everywhere comes from a mid-stage trial published in 2023. The larger trials that decide whether it gets approved are still running.

Why does it work better than Mounjaro or Ozempic?

It adds a third hormone the others do not use, and that one raises the energy you burn at rest rather than just curbing appetite. So weight comes off two ways instead of one. Worth being careful with head-to-head comparisons, though: retatrutide's 24.2% comes from a 48-week mid-stage trial of 338 people, while Mounjaro's 22.5% comes from a 72-week late-stage trial of 2,539. Different trials, different lengths, different sizes.

What did people in the trial lose?

The phase 2 trial reports group averages: an adjusted 8.7% of body weight in the 1 mg group and 24.2% in the 12 mg group at 48 weeks, against 2.1% on placebo. Individuals within those groups varied a lot, and nobody can predict an individual result. No study has tested whether any genotype changes response to retatrutide.

What do my genes have to do with it?

Retatrutide works through three receptors, and the genes that build those receptors vary from person to person. The one specific to it is GCGR, because it handles the energy-burning signal that Ozempic and Mounjaro do not use. No study has tested whether any of these variants changes response to retatrutide; a DNA report can show which versions you carry and what research links them to.

Watch

What clinicians and researchers say about Retatrutide

All 19 talks on Retatrutide

1 hr 30 minPeptide Expert: What Do Peptides Actually Do? (EXPLAINED) - Dr Alex TatemThe Diary of a CEO · PodcastBPC-157TB-500MOTS-c

15 minRetatrutide Isn't a Weight Loss Drug — Here's What It Really Does (Weightloss Dr. Explains)Kevin Joseph · ClinicianRetatrutideTirzepatideSemaglutide

11 minDr. Explains Why Retatrutide is KING of Fat Loss PeptidesAshley Froese · EducatorRetatrutideTirzepatideSemaglutide

Learn more about Retatrutide

peptide guides

In depth

Retatrutide: what the phase 3 trials found, and why it is not approved

9 min read

comparisons

In depth

What the research says about your variants.

The report

Which Retatrutide variants do you carry?

Your report reads the DNA file you already have against the published research on 31 peptides, marker by marker, and says what that research does and does not show.

Read my DNA, $99

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