Retatrutide

Overview

Retatrutide is an investigational once-weekly injectable peptide that activates three receptors at once — GIP, GLP-1, and glucagon — a step beyond the dual GLP-1/GIP mechanism of tirzepatide. In a published Phase 2 obesity trial it produced large average weight reductions (up to roughly 24% at 48 weeks at the highest dose), and a Phase 2a substudy showed substantial reductions in liver fat. The human evidence is genuinely promising but still mid-stage: as of 2026 the pivotal Phase 3 program (TRIUMPH) is ongoing and the drug is NOT FDA-approved for any indication. Developed by Eli Lilly. Treat it as an experimental agent whose long-term efficacy and safety are not yet established.

Commonly Reported Uses

These are uses commonly discussed or marketed by users and vendors — not a list of proven or approved benefits, and not a recommendation.

• Weight loss / obesity (investigational; Phase 2 human data only, not FDA-approved)
• Type 2 diabetes glycemic control (investigational; Phase 2 human data only)
• Metabolic dysfunction-associated steatotic liver disease / liver fat reduction (investigational; Phase 2a human data only)

What to Track

Data points you and your clinician might monitor. For observation only — not a diagnostic protocol.

• Smart scale — weight and body-fat % trend over the measurement period
• InBody/DEXA — skeletal muscle mass vs. fat mass, to watch for lean-mass loss during rapid weight loss
• Labs — HbA1c and fasting glucose if a clinician is monitoring glycemic effects
• Subjective — daily appetite, nausea, and GI tolerability check-ins
• WHOOP — resting heart rate and HRV trend (dose-dependent heart-rate increases were seen in trials)

Sources & References

1. [1]Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial (NEJM, 2023)
2. [2]Triple hormone receptor agonist retatrutide for MASLD: a randomized phase 2a trial (Nature Medicine, 2024)
3. [3]Retatrutide — Wikipedia