TRIUMPH-1: Retatrutide in Participants With Obesity or Overweight
The first Phase 3 obesity trial of retatrutide, a triple GIP/GLP-1/glucagon receptor agonist also sold in research form as GLP-3RT. This page is a good illustration of something important: a trial's registry record and its published journal results don't always update on the same timeline — see the comparison below.
Randomized, double-blind, placebo-controlled, Phase 3, 80-week treatment period with extension
2,335 adults with obesity or overweight, including sub-cohorts with knee osteoarthritis and obstructive sleep apnea
Once-weekly subcutaneous retatrutide at multiple doses vs. placebo
What the registry says
Status: Completed (actual completion April 2026). At the time of writing, ClinicalTrials.gov's structured results module for this record does not yet show posted results — a common and normal lag, not a red flag by itself.
What published research has found
Jastreboff et al., New England Journal of Medicine, 29 September 2026: average weight loss at 80 weeks of 28.3% on the 12mg dose (25.0% including everyone randomised), with 45.3% of participants on that dose losing 30% or more of body weight. A blinded extension in participants with BMI ≥35 showed 30.3% average loss by 104 weeks.
This is exactly the distinction this page exists to make clear: the registry and the peer-reviewed literature are two different records, and relying on only one can give you an incomplete picture in either direction.
What This Trial Tells Us
- A large, well-powered, peer-reviewed Phase 3 trial found a substantial average weight reduction with retatrutide in adults with obesity, published in one of medicine's most rigorous journals.
- Retatrutide (as GLP-3RT) is one of the few compounds in this space with genuine, major Phase 3 human trial data behind it.
What It Does NOT Tell Us
- Retatrutide is not currently FDA, MHRA, or EMA approved for any use — a large positive Phase 3 result is a step toward approval, not approval itself.
- This trial doesn't establish safety or efficacy outside the obesity/overweight population and doses studied here.
- Long-term safety beyond the trial's follow-up window remains unknown, which is exactly what the related TRIUMPH-Outcomes cardiovascular/kidney trial (NCT06383390, still active) is designed to help establish.