What does Retatrutide do?

The source presents Retatrutide as an investigational weekly injectable peptide active at GIP, GLP-1, and glucagon receptors. It reports Phase 2 mean weight reduction of approximately 24 percent of body weight at 12 mg and also lists Phase 3 development information.

How does Retatrutide work?

The source associates GLP-1 activity with appetite and gastric-emptying effects, GIP activity with insulin response and adipose nutrient handling, and glucagon activity with hepatic energy expenditure and fat burning. It says the relative contribution of these pathways in humans remains unresolved.

Is Retatrutide FDA approved?

The source states that Retatrutide was not FDA approved as of 2026. It lists a Phase 3 TRIUMPH-1 update and anticipated NDA submission timing from late 2026 to Q1 2027; neither is FDA approval.

What side effects are reported for Retatrutide?

Reported effects include dose-related nausea, diarrhea, vomiting, constipation, and heart-rate increases. The source additionally lists hypersensitivity reactions, dysesthesia, and rare pancreatitis, while noting that individual experience may vary with dose, duration, and personal health factors.

What dosing information is listed for Retatrutide?

The source's community entry lists 4-12 mg weekly, a 1-12 mg weekly (titrate up slowly) range, and once-weekly scheduling. These are retained source data, not individualized directions.

Weight Loss Clinical Trials - human trials under way

Retatrutide

Also known as: LY3437943, Triple G

At a glance

PeptiGuide dataset · reviewed Aug 2026

What it is

An investigational three-receptor peptide in Phase 3 obesity research.

Status

Clinical Trials

Evidence level: human studies

Typical dose

4–12mg

Subcutaneous injection weekly

Researched for

Weight loss, metabolic syndrome, liver fat reduction

Trial progress

PrePreclinical
IPhase I
IIPhase II
IIIPhase III
IVPhase IV
FDAFDA approved

Phase III - Emerging human evidence with important limitations

Use the tools

In plain language

Retatrutide is a once-weekly injectable with GIP, , and glucagon receptor activity; the source labels it a triple-G .
The source reports Phase 2 mean weight reduction near 24 percent of body weight at 12 mg and lists Phase 3 development.
A May 2026 TRIUMPH-1 update reports 28.3 % at 80 week on 12 mg; 45 % reached 30 % or more body-weight loss.
The source identifies Eli Lilly as developer, calls the molecule investigational, and states it is not FDA approved.
Listed research areas include weight loss, metabolic syndrome, and liver fat reduction.

How it's thought to work

Retatrutide is described as an at GIP, , and glucagon receptors. The source links GLP-1 signaling to lower appetite and delayed stomach emptying, GIP to insulin response and nutrient handling by fat tissue, and glucagon receptor activity to hepatic energy expenditure and fat burning. It emphasizes that the individual contribution of each receptor in humans is still uncertain.

What the research shows

Where the research stands

According to the source summary, Jastreboff and colleagues reported a 2023 NEJM Phase 2 randomized trial involving 338 adults with obesity but no type 2 diabetes. The 48 week trial reported a mean reduction close to 24 percent at 12 mg, with no clear plateau by that endpoint. It also reports that a large majority of participants with baseline prediabetes had normal blood sugar at follow-up. Nausea, vomiting, and diarrhea predominated and were described as dose-dependent. The summary says larger, longer Phase 3 work was intended to examine durability and safety.

What it shows

✓ Human studies

Emerging human evidence with important limitations

△ Limitations

Study protocols describe research and are not dosing recommendations.

Bottom line: Source-reported Phase 3 TRIUMPH-1 pivotal trial update (May 2026): 28.3 % mean weight loss at 80 week with 12 mg, and 45 % of patients lost 30 % or more. It calls this the largest Phase 3 obesity-drug loss result and expects an NDA submission late 2026–Q1 2027. Not FDA Approved

Typical dosing

CommunityCommunity dataset

4–12 mg

weekly

1 mgfull range seen12 mg

The community record also names 1-2 mg as a starting amount and identifies gastrointestinal effects as dose-related.

Research dosing

Study-specific protocolsHuman trials under way - protocols are study-specific

Doses observed in studies

0.5mg weekly (starting)

Phase 2 T2D Trial, Lancet 2023 - 0.5mg maintenance arm with no escalation

Study protocols describe research and are not dosing recommendations.

Duration: Long-term use expected
Administration: Subcutaneous injection weekly

Timing & administration

Best time to take

Morning, same day each week

Once weekly, same day and time

Food recommendation

With or without food

Why this timing?

The source suggests morning timing so tolerability can be observed and emphasizes keeping the weekly schedule consistent.

Possible side effects

Not everyone experiences these. Individual responses vary with dose, duration, and personal factors.

Nausea (dose-related)
Diarrhea
Vomiting
Constipation
Heart rate increases
Hypersensitivity reactions
Dysesthesia - skin sensitivity/tingling (~21% at highest dose, TRIUMPH-4 data)
Pancreatitis (rare)
Currently in Phase 3 trials

Not everyone experiences side effects, and severity can vary by context, purity, route, and individual health factors.

Sources

PubMed ClinicalTrials.gov FDA.gov

Frequently asked questions

Sequence

Tyr-Aib-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Ile-alpha-Me-Leu-Leu-Asp-Lys-[C20-diacid-gamma-Glu-AEEA-Lys]-Ala-Gln-Aib-Ala-Phe-Ile-Glu-Tyr-Leu-Leu-Glu-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser-NH2

One open dataset

Every fact on this page - doses, side effects, references - comes from the same PeptiGuide dataset that powers the Tracker, Compare, and the Lab.

Browse the dataset

Save to my research list Get updates on Retatrutide

Educational resource, not medical advice. Talk to your clinician before acting on anything here.

Community discussion

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Retatrutide

In plain languageIn plain language

How it's thought to workHow it's thought to work

What the research showsWhat the research shows

Typical dosing

Research dosing

Timing & administrationTiming & administration

Possible side effectsPossible side effects

SourcesSources

Frequently asked questionsFrequently asked questions