IGF-1 LR3 (Insulin-like Growth Factor-1 Long R3)
A modified IGF-1 with R3 substitution and N-terminal extension reducing IGFBP binding, increasing half-life and potency 2-3x over native IGF-1.
How it works
Activates IGF-1R while evading IGFBP sequestration. Triggers PI3K/Akt/mTOR for protein synthesis, satellite cell proliferation, and amino acid uptake into muscle.
Key facts
- Molecular weight: 9,111 Da
- Half-life: 20-30 hours (vs 15 min native)
- Bioavailability: High (SubQ/IM)
- Storage: Lyophilized: -20°C. Reconstituted: 2-8°C for 21 days.
Dosing overview
- Typical dose: 20-50 mcg
- Frequency: Daily (post-workout)
- Duration: 4-6 weeks
- Route: Subcutaneous or intramuscular injection
Protocol notes
- Run 20-50 mcg daily, typically right after training.
- Often injected bilaterally/locally into the muscles just trained for a localized growth signal.
- Kept to short 4-6 week blocks due to limited safety data.
Reported benefits
- Potent anabolic effects
- Hyperplasia (new muscle cells)
- Extended half-life
- Enhanced recovery
- Improved nutrient partitioning
- Satellite cell activation
Possible side effects
- Hypoglycemia risk
- Gut growth (prolonged)
- Joint pain
- Tumor promotion (theoretical)
- Water retention
Research
- IGF-1 LR3 pharmacokinetics and muscle anabolism (2020): LR3 modification increased bioactivity 300% with proportional protein synthesis increases.
- Local IGF-1 for muscle hypertrophy (2019): Site-specific injection produced 15% greater hypertrophy via satellite cell activation.
Community reviews of IGF-1 LR3
- measured_mike rated it 5/5 - Noticed clear benefits within weeks: Added IGF-1 LR3 to my protocol about 4 months ago and it has earned its place. The benefits became noticeable around week 2-3 and have been consistent since. What I appreciate about this compound is the predictability. It does what the research suggests it should do, at roughly the timeline you would expect. No surprises, no dramatic swings, just steady improvement. No notable side effects to report at my dose. Sourcing is always the challenge with research compounds, insist on third-party testing. Storage and reconstitution per standard protocols. Plan to continue.
- biohack_bree rated it 5/5 - Genuinely effective after 2 weeks: Been using IGF-1 LR3 for about 2 weeks and the results are clear. Not overnight dramatic, but a steady, consistent improvement that became undeniable by the end of the first month. The mechanism makes sense based on what I have read in the literature, and my subjective experience matches the expected timeline. Benefits built gradually and plateaued at a good level. Side effects were minimal to none at the dose I used. Followed proper protocols for sourcing, storage, and administration. Would recommend to others who have done their research and have realistic expectations.
- peptide_path_pam rated it 5/5 - Solid compound with real results: Been using IGF-1 LR3 for about 6 weeks and the results are clear. Not overnight dramatic, but a steady, consistent improvement that became undeniable by the end of the first month. The mechanism makes sense based on what I have read in the literature, and my subjective experience matches the expected timeline. Benefits built gradually and plateaued at a good level. Side effects were minimal to none at the dose I used. Followed proper protocols for sourcing, storage, and administration. Would recommend to others who have done their research and have realistic expectations.
- biohack_bree rated it 4/5 - Worth adding to the protocol: IGF-1 LR3 has been a worthwhile addition. I am data-driven and tracked relevant markers before, during, and after. The improvement is measurable and correlates with the intervention timeline. What sets this apart from some compounds I have tried is the consistency. Benefits did not fluctuate wildly or disappear. They built up and maintained. That gives me confidence in the mechanism. Tolerance has been excellent. Nothing in my bloodwork or subjective experience raised any flags. This is the kind of compound that does its job quietly without causing problems. Exactly what you want.
- jason482 rated it 5/5 - Leaner, fuller, but the hunger was mad: I ran IGF-1 LR3 for about 12 weeks while trying to pack on useful size after years of fireground wear and tear and lifting in Ireland. For me it seemed to tighten recovery and add a fuller look fast, but the hunger got a bit savage and I had to keep food dead on or I felt flat.
- evan_w rated it 5/5 - fastest I noticed fuller training days in years: the biggest thing for me was how much fuller and harder my training days felt after a few weeks, i’m a 50 something guy in the midwest, working freelance and trying to keep my strength moving up without beating myself up in the process, and igf-1 lr3 seemed to help me recover between sessions in a way i could actually notice, for what it is worth. i ran it about 10 weeks, and my lifts felt more productive, like i could push a little more without dragging the next day. that was the part that mattered most to me, because staying useful in the gym is half the battle at my age.
Compare IGF-1 LR3
Research and educational reference only. Not medical advice.