Research Reference
A next-generation investigational weight-loss compound by Eli Lilly · Updated May 2026
What is it
A once-weekly injectable "triple agonist" — a single peptide that simultaneously activates three hormone receptors to reduce appetite, burn more calories, and control blood sugar. It is not yet FDA-approved.
How it works — 3 receptors, 1 drug
Appetite & digestion
Insulin & appetite
Energy expenditure
The glucagon component would normally raise blood sugar — but GLP-1 & GIP cancel that risk while preserving the metabolic rate boost. That tri-agonist balance is what makes retatrutide mechanistically unique.
TRIUMPH-1 Phase 3 topline results — May 21, 2026
NEWMean weight loss (52 mg · 80 wk)
28.3%
2,339 participants
Extended loss (BMI ≥35 · 104 wk)
30.3%
≈ 85 lbs on average
Average pounds lost (highest dose)
70.3
lbs at 80 weeks
Participants achieving ≥20% loss
45.3%
of 12 mg group
First drug trial in history to produce bariatric-surgery-level weight loss (≥30%) at scale. 30% weight loss has historically been achievable only through bariatric surgery. These are topline results — not yet peer-reviewed or published in a journal.
TRIUMPH-1 · Weight loss by dose at 80 weeks
Earlier trial highlights
Phase 2 weight loss
24.2%
48 weeks · 12 mg
Liver fat reduced (Phase 2)
82%
at 24 weeks
HbA1c drop in T2D
−2.2%
50% reached <6.5%
TRIUMPH-4 (knee OA)
28.7%
weight loss + pain relief
Side effects
Common: Nausea · Vomiting · Diarrhea · Constipation — mainly during dose ramp-up, similar to other GLP-1 drugs.
Glucagon-specific: Modest heart-rate increase (~5 bpm). Generally mild and rarely leads to stopping treatment.
Development timeline
Up to 24.2% loss — largest ever seen in a peptide drug trial at the time.
28.7% loss confirmed + significant knee osteoarthritis pain relief.
28.3% avg loss at 80 wk · 30.3% extended · 45.3% ≥20% loss · 2,339 participants.
First drug to match bariatric surgery outcomes at scale.
T2D, cardiovascular outcomes, sleep apnea, maintenance dosing & more.
Not yet evaluated outside clinical trials. Topline data not yet peer-reviewed.
Sources
Eli Lilly press release May 21, 2026 · NEJM · Nature Medicine · ADA 2023 Scientific Sessions · TRIUMPH Phase 3 program.
R3TA supplies Retatrutide reference materials strictly for in-vitro, analytical, and laboratory research. These materials are not intended for human or animal consumption, diagnosis, treatment, cure, or prevention of any disease.
All researchers are responsible for compliance with applicable institutional, local, and federal regulations governing the purchase, handling, and use of research reference peptides.