Research Reference
Retatrutide
Triple-agonist (GLP-1 + GIP + glucagon) — next-generation weight loss
Research & educational purposes only. BioMaxFit does not sell, promote, or represent peptides in any way. We are strictly educational and recommend working with your doctor on anything health-related. The information below comes from published research and documents what has been studied, not what should be done. Many of these compounds are investigational and not approved by the FDA; possession or use outside an authorized clinical trial may be illegal in your jurisdiction. This is not medical advice.
Retatrutide is a triple-agonist peptide targeting GLP-1, GIP, and glucagon receptors simultaneously — producing the most pronounced weight-loss data from any metabolic peptide studied to date.
Community-reported protocols start at 0.25–0.5 mg/week and titrate to 1.5–4 mg/week over 8–12 weeks as GI tolerance is assessed. Phase 2 trials used up to 12 mg/week and produced 24.2% body weight loss at 48 weeks — community protocols are deliberately more conservative.
Retatrutide is an investigational drug not approved by the FDA. Possession or use outside an authorized clinical trial may be illegal in your jurisdiction.
Dosing Reference
Reconstitution
Add 2 mL bacteriostatic water to the 10 mg vial. Resulting concentration: 5 mg/mL.
| Dose | Syringe Units | mL Volume | Schedule |
|---|---|---|---|
| 0.5 mg | 10 units | 0.1 mL | WeeklyStart dose (weeks 1-2) |
| 1 mg | 20 units | 0.2 mL | WeeklyWeeks 3-4 |
| 2 mg | 40 units | 0.4 mL | WeeklyWeeks 5-8 |
| 4 mg | 80 units | 0.8 mL | WeeklyTarget (weeks 9+) |
| 8 mg | 160 units | 1.6 mL | WeeklyAdvanced |
Math assumes U-100 insulin syringes (1 mL = 100 units). Verify your syringe matches before use. Round half-units to the nearest visible mark.
Reconstitution
Reconstitution depends on vial size. For a 10 mg vial with 2 mL bacteriostatic water, the concentration is 5 mg/mL; a 1 mg dose draws to 20 units (0.2 mL). For a 20 mg vial with 2 mL, the concentration is 10 mg/mL; a 2 mg dose draws to 20 units (0.2 mL).
Gently swirl — do not shake. Refrigerate at 2–8°C and use within 28 days.
Cycling Protocol
Community protocols titrate gradually from 0.25–0.5 mg/week up to 1.5–4 mg/week over 8–12 weeks as GI tolerance is assessed. The triple-agonist mechanism (GLP-1 + GIP + glucagon) can cause more intense initial GI side effects than single-target agonists, so conservative titration is emphasized.
The trial-published ceiling is 12 mg/week; community protocols stay well below this. Some users self-report continuing until a goal is reached, then cycling off.
Routes of Administration
Subcutaneous injection (only route): Abdomen or thigh, using a 29–31 gauge insulin syringe. Weekly dosing cadence. Rotate injection sites.
Stacking Protocols
Retatrutide is typically run as a standalone metabolic protocol. Community sources describe combining it with structured nutrition and resistance training, and tracking fasting insulin, HOMA-IR, lipid panels, and body composition rather than stacking with other incretin agonists.
Side Effects & Safety
- GI effects (most common): Nausea, diarrhea, constipation, reduced appetite — typically most pronounced during titration and dose-dependent
- Injection site reactions — redness or mild pain
- Fatigue or malaise — occasionally during dose escalation
- Heart rate increase — noted in trial data, monitor if relevant
- Dehydration risk — GI fluid loss; maintain hydration
Investigational drug not FDA-approved. No long-term community safety data exists at trial-level doses.
Research Basis
Retatrutide is a triple-agonist targeting GLP-1, GIP, and glucagon receptors simultaneously.
Phase 2 trial data: Doses up to 12 mg/week produced 24.2% body weight loss at 48 weeks — the most pronounced weight-loss data from any metabolic peptide studied to date.
Community protocols are deliberately more conservative than the trial ceiling, titrating to 1.5–4 mg/week based on tolerance. The triple mechanism (adding glucagon agonism to the GLP-1/GIP dual action of tirzepatide) is hypothesized to drive additional energy expenditure alongside appetite suppression.