GLP-1 / GIP / glucagon triple agonist
Investigational once-weekly injectable for obesity/metabolic disease (Eli Lilly, LY3437943).
| Class / type | GLP-1 / GIP / glucagon triple agonist |
|---|---|
| Category | Metabolic & Weight |
| Status (Jul 2026) | Investigational |
Retatrutide (Lilly code LY3437943) is an experimental once-weekly injectable that hits three metabolic receptors at once. It has generated intense interest because its trial weight-loss numbers are the highest reported for this drug class to date.
Crucially, it is not approved. It is still in Phase 3 testing, so its long-term safety is not established and any 'retatrutide' sold online is unapproved, unregulated material.
Retatrutide agonizes the GLP-1 and GIP receptors (like tirzepatide) and adds glucagon-receptor activity. The glucagon arm is thought to raise energy expenditure and fat oxidation, potentially adding a fat-burning effect on top of the appetite suppression that GLP-1/GIP drugs provide.
In a Phase 2 obesity trial published in 2023, participants on the highest dose (12 mg) lost about 24% of body weight at 48 weeks - a striking result that beat existing approved drugs in cross-trial terms. Phase 3 (the TRIUMPH program) is underway to confirm efficacy and safety.
Because the pivotal Phase 3 data and regulatory review are not complete, these figures should be read as promising but not yet confirmed at approval standard.
The largest average weight loss reported for this class so far, with strong metabolic and (in studies) liver-fat improvements.
The added glucagon mechanism may help people who plateau on GLP-1/GIP drugs, though this is still being studied.
GI effects (nausea, constipation) during dose escalation are common, as with other incretin drugs.
Trials have reported dose-dependent increases in resting heart rate, plus fatigue and, in some participants, a tingling or sunburn-like skin sensation. Long-term safety is unknown, it is not approved, and gray-market material carries purity and dosing risks.
There is no approved retatrutide product and no established, sanctioned dosing for human use. Realistic timelines put possible FDA decisions no earlier than 2027-2028, pending trial results.
Dramatic appetite reduction and unusually large fat loss; some report more energy.
NOT FDA-approved. Phase 3 (TRIUMPH); possible approval ~2027-2028. Anything sold now is gray-market / research-use-only.