Retatrutide: research overview

Triple GLP-1/GIP/Glucagon receptor agonist. 39 amino acids. ~6-day half-life. First-in-class metabolic compound.

GLP-1 analogue. Molecular weight 4,731.4 Da; half-life 6 d. Reference material compiled from the published literature. For laboratory research only; nothing on this page is medical advice or a claim about a product.

How it is studied

A 39-amino-acid synthetic peptide that is a triple agonist of GLP-1, GIP, and glucagon receptors. In research literature, retatrutide is studied for concurrent incretin signaling, lipolysis through the glucagon arm, and hepatic glucose modulation. Published clinical trials report substantial body weight reductions of 24–30% over 48–68 weeks alongside improvements in liver fat and cardiovascular markers.

Retatrutide is a 39-amino-acid linear synthetic peptide developed as the first triple agonist of GLP-1, GIP, and glucagon receptors. The fatty-acid linker enables albumin binding and a ~6-day plasma half-life. It represents one of the most extensively studied next-generation incretin compounds in metabolic research.

Half-life, with its caveats

~6 days in humans (≈144 h, range 108–168 h across phase 1b/2 trials). Long t½ driven by a C20 fatty-diacid albumin-binding linker — not PEGylation. Urva et al., Lancet 2022.

How to read this page

Mechanism describes what the published studies tested, not what a product does.
Reported research areas list where the compound has been studied. They are not indications.
Dose ranges are what the literature reports, quoted for reference. They are not dosing advice.
Co-factor studies carry PubMed citations; open the source before relying on a figure.

Co-factors

Compounds studied alongside it

Sparse literature

Compounds identified in published research as sharing pathways with Retatrutide, or studied alongside it in trials. Reference material only — not a recommendation, not medical advice. Citations link to PubMed.

Dietary protein (and resistance training)

Whole-food protein

Shared mechanism

Rapid pharmacologic weight loss reduces both fat mass and lean mass; protein intake is the primary nutritional input that supports muscle protein synthesis

Retatrutide-specific co-factor literature is essentially absent as of mid-2026 (phase 2 trials completed 2023-2024, phase 3 ongoing). The closest applicable evidence is the GLP-1/GIP/glucagon receptor agonist class signal: pharmacologic weight loss is accompanied by meaningful losses of lean body mass, reported at 15-40% of total weight lost in narrative reviews of GLP-1 RA outcomes. Protein intake and resistance training are the most commonly described mitigation strategies in this literature. Retatrutide produced 24% weight reduction at 48 weeks in the Jastreboff phase 2 trial, the largest magnitude in the class to date, so the lean-mass concern extrapolates directly. Studied alongside the drug class, not yet alongside retatrutide specifically.

CitationsPMID 402890602025 PMID 379474892023

Vitamin D3 (cholecalciferol)

Cholecalciferol

Shared mechanism

Reduced caloric intake during incretin-induced satiety lowers dietary vitamin D; concurrent bone mineral density decline during weight loss compounds the deficiency signal

Vitamin D deficiency is the most commonly reported micronutrient abnormality in GLP-1 RA users in a 2026 narrative review (~7.5% at 6 months, ~13.6% at 12 months), and retatrutide as a triple incretin agonist shares the appetite-suppression and reduced caloric intake pathway driving that signal. Vitamin D deficiency is separately associated with reduced bone mineral density during rapid weight loss, which observational data has flagged for GLP-1 RAs without diabetes. Studied alongside the drug class through deficiency surveillance rather than head-to-head supplementation RCTs in retatrutide-treated populations.

CitationsPMID 415499122026

Caveat

Retatrutide-specific cofactor literature is genuinely sparse — the molecule completed phase 2 in 2023 and phase 3 (TRIUMPH-1, TRIUMPH-2) was still ongoing in mid-2026. All cofactor evidence here is extrapolated from the GLP-1 RA class (semaglutide, tirzepatide, liraglutide). Consider as provisional until retatrutide-specific micronutrient surveillance data appears.

All reading