Retatrutide, sometimes shortened to “Reta”, is one of the most talked-about peptides in research on metabolism, appetite and body weight. It is frequently compared with the well-known GLP-1 medicines Ozempic, Wegovy and Mounjaro, so this guide explains how they are alike and how they differ, alongside factual information on what Retatrutide is, how it works, what clinical trials have reported and where it stands with regulators.
This article is for educational purposes only and is not medical advice or a recommendation. All products sold by Evil Peptides are for laboratory research use only.
Key points
- Retatrutide is a synthetic triple agonist of the GLP-1, GIP and glucagon receptors.
- It was developed by Eli Lilly under the code name LY3437943.
- Phase 2 results were published in the New England Journal of Medicine in 2023.
- It is investigational and is not approved by the FDA, the EMA or the MHRA.
What is Retatrutide?
Retatrutide is a synthetic peptide classed as a triple agonist: a single molecule designed to activate three hormone receptors at once, namely GLP-1, GIP and glucagon. All three pathways are involved in regulating appetite, insulin secretion and energy metabolism. The compound was developed by Eli Lilly, studied under the designation LY3437943, and has reached advanced stages of clinical research.
How is it thought to work?
The rationale behind a triple agonist is to combine three complementary actions in one molecule:
- GLP-1: a pathway involved in satiety and blood glucose regulation.
- GIP: a second gut hormone that influences metabolism and the insulin response.
- Glucagon: involved in energy expenditure and hepatic metabolism.
It is this combination that distinguishes Retatrutide from compounds acting on only one or two of these pathways.
What has clinical research reported?
Notable results from a Phase 2 trial were published in 2023 in the New England Journal of Medicine. Participants in the highest-dose group showed an average reduction in body weight of around 24% over 48 weeks. These findings must be read in context: they were obtained in a controlled clinical trial under medical supervision, using a compound that is investigational and unapproved for therapeutic use. As with related compounds, side effects were also recorded, mainly gastrointestinal.
Retatrutide compared with Ozempic, Wegovy and Mounjaro
The compounds most often discussed under the “weight-loss injections” banner differ chiefly in how many receptors they activate:
| Compound | Mechanism | Brand names |
|---|---|---|
| Semaglutide | Single agonist (GLP-1) | Ozempic, Wegovy |
| Tirzepatide | Dual agonist (GLP-1 + GIP) | Mounjaro (Zepbound in the US) |
| Retatrutide | Triple agonist (GLP-1 + GIP + glucagon) | None yet; still in clinical research |
For more on the wider family, see our guide to GLP-1 “weight-loss injections”.
Regulatory status
At the time of writing, Retatrutide is an investigational compound and has not been approved for therapeutic use by the US FDA, the European Medicines Agency or the UK’s MHRA. Compounds sold for research purposes are no substitute for medical advice or treatment and must not be used in humans. Anyone with questions about weight management should speak to a qualified doctor.
Frequently asked questions
What does “Reta” refer to?
It is simply an informal shorthand for Retatrutide.
Is Retatrutide FDA-approved?
No. It remains in clinical research, and research-grade material is supplied for laboratory use only.
How does Retatrutide differ from Ozempic or Mounjaro?
Mainly in the number of receptors it targets. Ozempic and Wegovy (semaglutide) act on one receptor, Mounjaro (tirzepatide) on two, and Retatrutide was designed to act on three.
Research material is listed as Retatrutide 20mg and Retatrutide 40mg. For concentration and unit conversions in laboratory work, use our peptide calculator.
Research use only: this article is general and educational and is not medical advice. All products sold by Evil Peptides are intended solely for laboratory research and are not for human or veterinary use.