IGF-1 LR3
Also known as: Long R3 IGF-1, Insulin-like Growth Factor 1 Long R3
A modified version of IGF-1 with 13 extra amino acids and one substitution that makes it about 2-3x more potent and longer-lasting than natural IGF-1. It stays active for 20-30 hours instead of 12 hours. Used in research for muscle growth and recovery but carries real risks including hypoglycemia and potential cancer concerns.
How it works
IGF-1 LR3 binds to IGF-1 receptors on cells throughout your body, activating pathways that stimulate protein building, cell repair, and energy use. The modifications make it bind less tightly to IGF binding proteins, so more of it stays free and active in the bloodstream for 20-30 hours (vs 12 hours for natural IGF-1). This makes it about 2.5x more anabolic than regular IGF-1 in animal studies.
Common uses
- Muscle growth and recovery (research)
- Lean mass preservation
- Fat metabolism support
- Tissue repair (research)
Side effects
- Hypoglycemia (low blood sugar, can be serious)
- Muscle and joint pain
- Nausea
- Headaches
- Fluid retention
- Insulin resistance with prolonged use
- Potential increased risk of certain cancers (elevated IGF-1 is associated with tumor growth)
- Localized muscle growth at injection sites
Key research
- Rodent studies show IGF-1 LR3 is approximately 2.5x more anabolic than standard IGF-1
- Research demonstrates extended half-life of 20-30 hours vs 12 hours for native IGF-1
- Epidemiological studies link chronically elevated IGF-1 levels to increased risk of certain cancers
- No controlled human clinical trials for muscle growth or anti-aging applications
Safety notes
- Not FDA-approved for any medical use
- Hypoglycemia is a real and potentially dangerous risk, especially at higher doses
- Chronic IGF-1 elevation is linked to increased cancer risk in observational studies
- Banned by WADA for athletic competition
- Should never be used without medical supervision and blood sugar monitoring
- Not recommended for anyone with active or history of cancer
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