Reviewed Mar 2026 | Sources: PubMed

Tirzepatide vs Retatrutide: Head-to-Head Comparison

Tirzepatide is an FDA-approved dual GIP/GLP-1 agonist achieving up to 22.5% weight loss. Retatrutide is an investigational triple agonist (GIP/GLP-1/glucagon) showing up to 24.2% weight loss in Phase 2 — the highest ever recorded. Tirzepatide is available now; retatrutide is still in Phase 3 trials.

Side-by-Side Comparison

DimensionTirzepatideRetatrutide
Evidence LevelLevel A — Phase 3 RCTs (SURMOUNT, SURPASS)Level B — Phase 2 RCT; Phase 3 ongoing
FDA StatusApproved for T2D (Mounjaro) and obesity (Zepbound)Not approved; Phase 3 trials (TRIUMPH program)
Weight Loss EfficacyUp to 22.5% (SURMOUNT-1 at 72 weeks)Up to 24.2% (Phase 2 at 48 weeks)
MechanismDual agonist: GIP + GLP-1 receptorsTriple agonist: GIP + GLP-1 + glucagon receptors
Liver Fat ReductionModerate liver fat reduction observedSignificant liver fat reduction via glucagon activation
AvailabilityAvailable by prescription nowNot yet available; expected 2026-2027
Evidence Level
Tirzepatide
Level A — Phase 3 RCTs (SURMOUNT, SURPASS)
Retatrutide
Level B — Phase 2 RCT; Phase 3 ongoing
FDA Status
Tirzepatide
Approved for T2D (Mounjaro) and obesity (Zepbound)
Retatrutide
Not approved; Phase 3 trials (TRIUMPH program)
Weight Loss Efficacy
Tirzepatide
Up to 22.5% (SURMOUNT-1 at 72 weeks)
Retatrutide
Up to 24.2% (Phase 2 at 48 weeks)
Mechanism
Tirzepatide
Dual agonist: GIP + GLP-1 receptors
Retatrutide
Triple agonist: GIP + GLP-1 + glucagon receptors
Liver Fat Reduction
Tirzepatide
Moderate liver fat reduction observed
Retatrutide
Significant liver fat reduction via glucagon activation
Availability
Tirzepatide
Available by prescription now
Retatrutide
Not yet available; expected 2026-2027

Peptide Overviews

Tirzepatide

AFDA Approved

Tirzepatide is the first dual GIP and GLP-1 receptor agonist, approved by the FDA for type 2 diabetes (Mounjaro) and chronic weight management (Zepbound). Achieves unprecedented weight loss in clinical trials.

Weight LossFDA Approved
View full Tirzepatide profile →

Retatrutide

BHuman Studies

Retatrutide is an investigational triple-hormone receptor agonist developed by Eli Lilly. It simultaneously targets GIP, GLP-1, and glucagon receptors, achieving the highest weight loss ever reported in an obesity clinical trial — up to 24.2% at 48 weeks.

Weight LossNot Approved
View full Retatrutide profile →

Tirzepatide vs Retatrutide: FAQ

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No claims of therapeutic efficacy are made for substances that are not FDA-approved for the discussed indications. Research citations reflect published findings and do not imply endorsement.