What is Retatrutide?
Retatrutide (LY3437943) is Eli Lilly's triple GLP-1/GIP/glucagon receptor agonist in Phase III clinical trials. The TRIUMPH-4 trial (December 2025) achieved 28.7% average weight loss (71.2 lbs from a 248.5 lb baseline) at 68 weeks with 12mg — the highest weight loss efficacy recorded for any obesity medication to date. FDA approval is anticipated in 2026–2027.
Mechanism of Action
Triple receptor co-agonism: GLP-1R for appetite suppression and incretin effect, GIPR for improved insulin sensitivity, glucagon receptor for increased energy expenditure and hepatic fat oxidation — addressing obesity through three distinct metabolic pathways simultaneously
Target: GLP-1 receptor (GLP1R), GIP receptor (GIPR), Glucagon receptor (GCGR)
Research Indications
Clinical trials demonstrate significant body weight reduction with sustained benefit
Improves glycemic control and A1C levels in type 2 diabetes
Associated with reduced cardiovascular events in high-risk patients
Addresses multiple components of metabolic syndrome simultaneously
Research Protocols
These are commonly discussed research protocols — not medical advice. Consult a healthcare provider before use.
| Goal | Dose | Frequency | Route |
|---|---|---|---|
| Conservative Start (Week 1–4) | 0.5 mg | Once weekly | Subcutaneous injection |
| Low Maintenance (Week 4–8) | 1 mg | Once weekly | Subcutaneous injection |
| Standard Escalation (Week 8–12) | 2 mg | Once weekly | Subcutaneous injection |
| Moderate Weight Loss (Week 12–16) | 4 mg | Once weekly | Subcutaneous injection |
| Advanced Weight Loss (Week 16–20) | 8 mg | Once weekly | Subcutaneous injection |
| Maximum Efficacy (Week 20+) | 12 mg | Once weekly | Subcutaneous injection |
Peptide & Drug Interactions
Always consult your healthcare provider before combining with other compounds. Use our Interaction Checker for reference.
How to Reconstitute & Inject
Use bacteriostatic (BAC) water only. Avoid saline — may cause precipitation. Refrigerate and use within 28 days.
- 1
Remove Retatrutide vial from refrigeration and allow to reach room temperature (15–20 minutes)
- 2
Clean vial top with alcohol swab and allow to air dry completely
- 3
Using a sterile syringe, draw the calculated volume of bacteriostatic water (BAC water)
- 4
Inject BAC water slowly down the side of the vial — do not aim directly at the powder
- 5
Gently swirl in circular motions — DO NOT shake vigorously as this degrades the peptide
- 6
Allow 2–3 minutes for full dissolution — solution should be clear and colorless
- 7
Draw calculated dose into an insulin syringe for subcutaneous injection
- 8
Inject into abdomen, thigh, or upper arm. Rotate injection sites to prevent lipodystrophy
- 9
Store reconstituted solution refrigerated (2–8°C) and use within 28 days
What to Expect
Week 1–2
Initial appetite suppression may begin. Mild GI effects (nausea, fullness) as your body adapts.
Week 2–4
Noticeable reduction in food cravings and portion sizes. Early weight changes begin.
Week 4–8
Significant appetite control and steady weight loss. Improved blood sugar if applicable.
Week 8–16
Substantial weight reduction and enhanced energy. Metabolic markers begin improving.
Week 16–24
Major weight loss milestone with cardiovascular benefits and improved lipid profiles.
Week 24+
Maximum clinical efficacy. Comprehensive metabolic improvements and sustained benefits.
Side Effects & Safety
- Nausea (most common, typically dose-dependent and transient)
- Diarrhea or constipation during dose escalation
- Vomiting, especially when starting or increasing dose
- Reduced appetite and early satiety
- Injection site reactions (redness, bruising)
- Fatigue, particularly in early weeks
- Rare: Pancreatitis — discontinue immediately with severe abdominal pain
- Rare: Thyroid C-cell effects (contraindicated with MEN2 or thyroid cancer history)
FDA Status & Regulatory Info
Retatrutide (LY3437943) is Eli Lilly's triple GLP-1/GIP/glucagon receptor agonist in Phase III clinical trials. The TRIUMPH-4 trial (December 2025) achieved 28.7% average weight loss (71.2 lbs from a 248.5 lb baseline) at 68 weeks with 12mg — the highest weight loss efficacy recorded for any obesity medication to date. FDA approval is anticipated in 2026–2027.
Frequently Asked Questions
Research References
External links for education only. We do not control third-party content.
Community-reported data
The information below reflects self-reported experiences from PeptIQ app users. It is not clinical evidence and should not replace professional medical advice.
Community Intelligence
What 125 users report
Positive 99% · Neutral 1% · Negative 0%
Most reported benefits
Most reported side effects
Dose distribution
Median: 2000+ mcg · Most common: 2000+ mcg
Commonly stacked with
How repeat users are trending
Among repeat reporters, 100% said they felt similar to their last entry, 0% more positive, and 0% more negative.
Overall, repeat reporters leaned similar or mixed compared to their previous entry.
Median gap between entries: 51 days · Based on 45 repeat reporters
Share Your Experience
Rate Retatrutide in the PeptIQ app and help the community make informed decisions.
Research purposes only
This page is for educational reference. It is not medical or legal advice. Consult the FDA and a licensed healthcare professional for current regulations and individualized guidance.