Retatrutide (LY3437943) is a triple agonist of GLP-1, GIP, and glucagon (GCGR) receptors from Eli Lilly, representing the next generation beyond tirzepatide. Adding the glucagon component is a fundamental architectural decision: if GLP-1 reduces caloric intake and GIP improves insulin sensitivity, GCGR activation increases energy expenditure through enhanced thermogenesis and fatty acid oxidation in the liver. This is the first mechanism in the class acting simultaneously on both sides of the energy balance equation: intake and expenditure. Preclinical models show the glucagon component accounts for an additional ~5–7% weight reduction compared to tirzepatide.
Phase II clinical data stand out even against an impressive class: at 12 mg dose, body weight reduction reached 24.2% over 48 weeks — with no plateau reached by the end of observation, indicating a continuing effect. At 8 mg, 100% of participants lost ≥5% and 91% lost ≥10%; at 12 mg, 83% lost ≥15% — metrics previously considered unattainable for obesity pharmacotherapy. In parallel, all cardiovascular markers improved: systolic blood pressure, waist circumference, triglycerides, and glycemic control.
A key open question is the composition of lost mass: with aggressive weight reduction, the proportion of muscle loss is higher than with moderate loss. Preserving lean mass with 24% weight reduction requires an active supplemental protocol (resistance training, adequate protein); otherwise a significant portion of loss will come from muscle. The adverse event profile is classic for the incretin class: nausea, vomiting, diarrhea, manageable with titration. Phase III is ongoing.
⚖️ Weight reduction (record 24% over 48 wk, clinical): ★★★★★
🔥 Energy expenditure (unique GCGR component): ★★★★★
🍬 Cardiometabolic profile (BP, glucose, lipids): ★★★★☆
✅ Safety: ★★★☆☆ (GI profile of the class; Phase III; muscle preservation question open)
⚠️ Possible sensations and side effects: nausea, vomiting, appetite reduction; slow titration mandatory
🤝 Combinations (goal → stack)
💪 Weight + muscle preservation → Retatrutide + IGF-1 LR3
⚖️ Weight + amylin pathway → Retatrutide + Cagrilintide
🏋️ Recomposition + energy → Retatrutide + SLU-PP-332
| CAS number | 2381089-83-2 |
| Batch purity | 99.27 % |
Full information in our guide
https://peptideboost.club/guide/retatrutide
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