IGF-1 LR3
IGF-1 LR3 is a modified version of Insulin-like Growth Factor 1 with an extended half-life. Unlike natural IGF-1, the LR3 variant resists binding to IGF binding proteins, keeping it active in the bloodstream significantly longer. It promotes both muscle hypertrophy (larger cells) and hyperplasia (new cells), making it one of the most potent muscle-building peptides. It also enhances nutrient partitioning and recovery.
Frequency
5 days on, 2 days off
Cycle Length
4-6 weeks on, 4 weeks off
Route
Intramuscular
Research Level
Established
Goals
Dosing Protocol
100-200 mcg per injection (10-20 units). With standard reconstitution (1 mg in 1 mL), 0.01 mg per unit — 10 units = 100 mcg, 20 units = 200 mcg on a U-100 insulin syringe. 5 days on, 2 off.
Reconstitution
Add 1 mL bacteriostatic water to a 1 mg vial.
Timing
After meal / before gym.
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Potential Side Effects
- Hypoglycemia risk
- Joint pain
- Potential organ growth with chronic use
- Gut distension at high doses
Important Warnings
- Serious hypoglycemia risk — always eat around dosing
- Do not use with active cancer — potent growth factor
- WADA-prohibited substance
- Chronic high-dose use may cause organ enlargement
Research References
- Francis GL, et al. J Mol Endocrinol. 1992;8(3):213-223. doi:10.1677/jme.0.0080213
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Medical Disclaimer: This information is for educational purposes only and is not intended as medical advice. IGF-1 LR3 may be regulated differently in various jurisdictions. Always consult with a qualified healthcare provider before beginning any peptide protocol. PepStack Pro does not sell peptides or provide medical advice. Content reviewed by Dr. Seth Miller, MD.