Investigational
Retatrutide
The triple agonist pushing medical weight loss toward surgical results.
KEY EVIDENCE
TRIUMPH-1 · TRIUMPH-4
VIDEO LESSON
Status
Retatrutide is not FDA-approved and is available only in clinical trials. A regulatory filing is expected after the phase 3 TRIUMPH program.
What trials show
• Very large average weight loss in phase 3 trials
• Gastrointestinal side effects similar to other incretin medicines
• Early data on liver fat and knee osteoarthritis pain
Good to know
Products sold online as "research peptides" are unregulated, may be contaminated or mislabeled, and are not safe substitutes.
AT A GLANCE
Type
Medication
Brand names
Investigational (no brand name yet)
Status
Investigational
Reviewed by
Farhan Tahir, MD
Is this treatment right for you?
Prescription medicines and procedures need individual medical advice. Dr. Tahir’s team offers consults through Youthful Medicine.
How it works
An investigational weekly injection that activates GIP, GLP-1 and glucagon receptors. The glucagon signal is thought to raise energy use and clear liver fat.
What the evidence shows
Topline TRIUMPH-1 results (May 2026) reported a mean 28.3% weight loss at 80 weeks on the 12 mg dose, with 45.3% of participants losing at least 30% of body weight. TRIUMPH-4, in people with knee osteoarthritis, reported up to 28.7% weight loss at 68 weeks. Full peer-reviewed data are still pending.
Side effects & cautions
Not FDA-approved and available only in clinical trials. Gastrointestinal side effects were common, consistent with other incretin medicines. Avoid unregulated “research peptide” sources.
PRIMARY SOURCE
Eli Lilly. Retatrutide delivered powerful weight loss in pivotal Phase 3 obesity trial. May 21, 2026.
TYPICAL RESULT IN TRIALS
28.3% mean weight loss at 80 weeks (topline)
PHYSICIAN FIRST
Is this right for you?
Prescription treatments need a review of your history, labs and other medicines. Never start or stop one on your own.