Retatrutide
A peptide. Three receptors. Research only. Not a protocol. Say retatrutide, not RTA-3.
Simple words
A receptor is a protein on a cell. This chain can stick to three of them:
- GLP-1 — “I’m getting full.”
- GIP — another gut peptide after a meal.
- Glucagon — tells the liver to put sugar into the blood, and also affects how the body uses fat.
Semaglutide does one. Tirzepatide does two. Retatrutide does three. That is the only reason people stack those names.
What it is
A lab-made peptide from Eli Lilly. Not approved as a drug yet. On some sites the same powder is labeled GLP-3. That is a shop name, not a different molecule.
What researchers studied
Ania Jastreboff and colleagues published a phase 2 trial in the New England Journal of Medicine in 2023. Adults with obesity. People on retatrutide lost a lot of weight. Muscle loss became the next question people asked, because when weight falls fast, some of it is lean tissue. The paper is a mid-stage trial, not a finished approval package.
Papers
Jastreboff et al., 2023 — Phase 2. Retatrutide and body weight. New England Journal of Medicine.
What this is not
Not an approved pen. Not a muscle drug. This page does not tell you how much to take.
Related: semaglutide · tirzepatide