Retatrutide

In the phase 2 trial, the highest dose produced up to 24.2% body weight loss at 48 weeks — the largest reduction reported for any anti-obesity medication in trials to date. Phase 3 trials (the TRIUMPH program) are still ongoing to confirm this at scale, and retatrutide isn't approved by any regulator yet, so this remains trial evidence rather than a settled result.

Trials don't report a single moment when it 'starts working' — weight and HbA1c were tracked over many weeks, with phase 2 obesity data running to 48 weeks and phase 3 diabetes data to 40 weeks. Dosing is also stepped up gradually over roughly 16 weeks in some designs, so early weeks reflect a lower dose than later ones, which makes time-to-effect hard to separate from the escalation schedule itself.

This isn't addressed in the sourcing available here — the retatrutide trials tracked weight loss and HbA1c changes during dosing, not what happens after stopping. No discontinuation or rebound data specific to retatrutide is included, so what happens after stopping remains unanswered by the evidence gathered so far.

It's still in phase 3 trials — the TRIUMPH program — which haven't yet completed and reported the full results regulators require. It has shown strong phase 2 obesity results and phase 3 type 2 diabetes results, but regulatory filings are pending completion of that trial program, not yet submitted.

Gastrointestinal effects are the most common: nausea in 16 to 25%, diarrhea in 16 to 22%, and vomiting in 8 to 13%, generally reduced by starting at a lower dose and increasing gradually. Decreased appetite and a transient increase in heart rate are also reported. Because the glucagon component could theoretically raise blood sugar while the GLP-1/GIP components lower it, hyperglycemia is monitored in trials, and the full safety profile is still pending complete phase 3 data.

It isn't approved by any regulator, so there's no licensed medical use anywhere yet — it exists only as a trial drug and in unregulated vials sold online, which is part of why US poison-control centers reported a 265% jump in retatrutide-related calls in early 2026. As for sport: GLP-1 receptor agonists as a class are not on WADA's Prohibited List and don't require a therapeutic use exemption; the class was added to WADA's monitoring program instead, with whether to prohibit it under discussion ahead of the 2028 Olympics.

No storage data have been published for retatrutide specifically — it remains an investigational compound, so long-term stability of the powder or a reconstituted solution isn't public. Trial sites follow the sponsor's own handling protocol; its fatty-acid side chain, the same kind of modification used to extend other once-weekly peptides' stability, suggests it may be more robust than short, unmodified peptides, but that's an inference, not measured data for this specific drug.