Tirzepatide vs Retatrutide
How Tirzepatide and Retatrutide differ on mechanism, dosing, and the strength of the evidence behind each.
How this is graded
Every compound below carries a REGEN research grade, from S (regulatory approval behind the use it is bought for) down to F (no clinical evidence). Ordering follows that grade rather than search volume, so the compound at the top is the one with the most evidence, not the one most often sold. Doses are those reported in published protocols and are not recommendations.
Tirzepatide
Tirzepatide is a dual agonist that activates both GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 receptors, combining two incretin pathways for appetite suppression, improved insulin sensitivity, and weight loss. Trials show it produces greater average weight loss than semaglutide. Like other incretin mimetics it is titrated slowly to manage GI side effects. It strongly moves metabolic markers and is used as a standalone metabolic intervention. Monitor blood glucose, especially if combined with other glucose-lowering agents.
Retatrutide
Retatrutide (LY3437943) is an investigational triple receptor agonist that activates the GIP, GLP-1, and glucagon receptors, informally a ‘GLP-3’ for adding glucagon agonism on top of the dual mechanism of tirzepatide. The added glucagon activity raises energy expenditure alongside the appetite suppression and improved glucose control of the incretin pathways, and phase 2 trials reported some of the largest average weight reductions seen for any single agent to date. It is dosed once weekly subcutaneously and titrated slowly to manage gastrointestinal side effects. As an investigational compound it is not FDA-approved; monitor metabolic markers and titrate per protocol.
Evidence compared
| Tirzepatide | Retatrutide | |
|---|---|---|
| Research grade | Sgrade | Agrade |
| Reported dose | 2.5–15 mg | 1–12 mg |
| Frequency | 1x weekly (titrated) | 1x weekly (titrated) |
| Half-life | ~5 days | ~6 days |
| Routes | subcutaneous | subcutaneous |
| Tracked outcomes | Weight Loss, Immune Function, Body Composition, Muscle Growth, Sleep Quality | Weight Loss, Immune Function, Body Composition, Muscle Growth |
| Contraindications | personal/family history of medullary thyroid carcinoma, MEN 2, pancreatitis, pregnancy | personal/family history of medullary thyroid carcinoma, MEN 2, pancreatitis, pregnancy |
Which has more behind it
Tirzepatide carries the stronger evidence grade (S) against Retatrutide at A, which means more of what is claimed for Tirzepatide has been tested in humans. Both entries link through to the full reference, where the trial list and citations for each claim are set out in full.
Full Tirzepatide reference · Full Retatrutide reference
At a glance
| Compound | Grade | Reported dose | Half-life |
|---|---|---|---|
| Tirzepatide | Sgrade | 2.5–15 mg · 1x weekly (titrated) | ~5 days |
| Retatrutide | Agrade | 1–12 mg · 1x weekly (titrated) | ~6 days |
Frequently asked questions
Tirzepatide or Retatrutide, which has better evidence?
Tirzepatide carries the stronger evidence grade (S) against Retatrutide at A, which means more of what is claimed for Tirzepatide has been tested in humans.
Can Tirzepatide and Retatrutide be used together?
The catalog does not list Tirzepatide and Retatrutide as a common pairing. Combining compounds does not combine their evidence.
What doses are reported for Tirzepatide?
Published protocols report 2.5–15 mg, 1x weekly (titrated). This is what the literature describes, not a recommendation.
References
- Tirzepatide Once Weekly for the Treatment of Obesity
- Frías JP, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2). N Engl J Med. 2021;385(6):503-515.
- Comparison of tirzepatide and dulaglutide on major adverse cardiovascular events in participants with type 2 diabetes and atherosclerotic cardiovascular disease: SURPASS-CVOT design and baseline characteristics.
- Tirzepatide - StatPearls - NCBI Bookshelf
- Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022;387(3):205-216.
- Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes.
- Garvey WT, et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2). Lancet. 2023;402(10402):613-626.
- Mounjaro FDA Label
- Rosenstock J, et al. Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1). Lancet. 2021;398(10295):143-155.
- Effects of tirzepatide versus insulin glargine on kidney outcomes in type 2 diabetes in the SURPASS-4 trial: post-hoc analysis of an open-label, randomised, phase 3 trial.
- FDA Approves First Medication for Obstructive Sleep Apnea
- Nauck MA, D'Alessio DA. Tirzepatide, a dual GIP/GLP-1 receptor co-agonist for the treatment of type 2 diabetes with unmatched effectiveness. Cardiovasc Diabetol. 2022;21(1):66.
- Triple–Hormone–Receptor Agonist Retatrutide for Obesity, A Phase 2 Trial
- Jastreboff AM, et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity, A Phase 2 Trial. N Engl J Med. 2023;389:514-526.
- Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials.
- Appetite, eating attitudes, and eating behaviours during treatment with retatrutide in adults with type 2 diabetes: Results of a phase 2 study
- Rosenstock J, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial. Lancet. 2023;402(10401):529-544.
- Effects of retatrutide on body composition in people with type 2 diabetes. Lancet Diabetes Endocrinol. 2025.
- Efficacy and safety of retatrutide, a novel GLP-1, GIP, and glucagon receptor agonist. PMC. 2024.
- Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial.
- Once-Weekly Semaglutide in Adults with Overweight or Obesity
- Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatohepatitis. Nature Medicine. 2024.
- Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial.