IGF-1 LR3 is a modified version of insulin-like growth factor 1. Normal IGF-1 has a half-life of about 15 minutes. The LR3 modification extends it to 20-30 hours. IGF-1 is the downstream growth signal that HGH produces via the liver. Using IGF-1 LR3 skips the HGH step entirely and delivers the growth signal directly. This makes it potent for muscle hypertrophy but also means you bypass all the regulatory feedback your body uses to keep IGF-1 in check. Side effects include hypoglycemia (IGF-1 lowers blood sugar), gut distension at high doses, and theoretical cancer risk from sustained IGF-1 elevation. This is a serious compound for experienced users.
IGF-1 LR3 Protocol
Dose: 20-50mcg per day | Frequency: Once daily, post-workout preferred | Cycle: 4-6 weeks on, 4 weeks off | Route: SubQ or IM (site-specific)
Eat carbs within 30 minutes of dosing to prevent hypoglycemia. IGF-1 lowers blood sugar significantly. Post-workout timing takes advantage of the anabolic window. Do not use on an empty stomach.
IGF-1 LR3 Effects
Muscle hypertrophy (75%). Direct muscle growth stimulus through IGF-1 receptor activation. Promotes both hyperplasia and hypertrophy.
Recovery (60%). Faster recovery between training sessions from enhanced tissue repair signaling.
Fat loss (40%). Indirect fat loss through improved nutrient partitioning. Calories preferentially directed toward muscle.
Hypoglycemia risk (35%). IGF-1 lowers blood sugar. Not a benefit. Eat carbs around your dose to prevent crashes.
IGF-1 LR3 Side Effects
Hypoglycemia (30%). IGF-1 lowers blood sugar. Eat carbs within 30 minutes. Do not use on an empty stomach.
Water retention / joint pain (15%). Puffy joints, especially wrists and ankles. Dose-dependent.
Headache (10%). Mild headache. Usually transient.
Gut distension (5%). At higher doses over longer cycles. The "GH gut" concern. Keep doses moderate and cycles short.
IGF-1 LR3 Dosing by Use Case
Condition
Dose
Duration
Notes
Muscle hypertrophy (bodybuilding)
20-50mcg SubQ or IM daily, post-workout
4-6 weeks on, 4 weeks off
The primary use case. IGF-1 LR3 stimulates muscle growth directly through IGF-1 receptor activation. IM injection in the target muscle may enhance localized growth (debated). Always eat carbs around dosing. Hypoglycemia is the main acute risk.
Recovery enhancement
20-30mcg SubQ daily
4 weeks
Lower doses for recovery without aggressive muscle growth goals. IGF-1 supports tissue repair systemically. The extended half-life means you get sustained signaling throughout the day.
IGF-1 LR3 Results Timeline
Week 1-2, Fullness and pumps: Muscles feel fuller during training. Pumps are more pronounced. Hypoglycemia episodes if you are not eating enough carbs.
Week 2-4, Visible growth: Measurable increases in muscle size if training and nutrition are dialed in. Recovery between sessions noticeably faster.
Week 4-6, Peak effects, cycle off: Maximum hypertrophy benefits. Diminishing returns beyond 6 weeks as receptors desensitize. Cycle off for 4 weeks minimum.
Frequently Asked Questions About IGF-1 LR3
What is IGF-1 LR3?
IGF-1 LR3 (Long R3 Insulin-like Growth Factor 1) is a modified version of human IGF-1 with an extended half-life of 20-30 hours (vs ~15 minutes for native IGF-1). IGF-1 is the growth signal your liver produces when stimulated by growth hormone. LR3 skips the GH/liver step and delivers the growth signal directly. It is a research compound with no FDA approval.
What is the best IGF-1 LR3 dosage?
20-50mcg subcutaneously once daily. Post-workout timing is preferred. For a 1mg vial reconstituted with 1mL bacteriostatic water, 20mcg is 2 units and 50mcg is 5 units on a U-100 insulin syringe. Always eat carbs within 30 minutes of dosing. IGF-1 lowers blood sugar. Hypoglycemia on an empty stomach is a real risk.
What are the side effects of IGF-1 LR3?
Hypoglycemia (blood sugar crash) is the main acute risk. Eat carbs around your dose. Joint pain from water retention (15%), headache (10%), and gut distension at higher doses over longer cycles. Theoretical cancer risk from sustained IGF-1 elevation. This is not a beginner compound. The side effect profile is more serious than most peptides on this wiki.
IGF-1 LR3 vs HGH: what is the difference?
HGH stimulates your liver to produce IGF-1 (among other effects). IGF-1 LR3 IS the growth signal, delivered directly. HGH has broader effects: fat metabolism, sleep, skin, hair. IGF-1 LR3 is more targeted: muscle growth and tissue repair. HGH is slower-acting and systemic. IGF-1 LR3 is faster and more direct. HGH has decades of human data. IGF-1 LR3 has none.
How do you reconstitute IGF-1 LR3?
Add 1mL of bacteriostatic water to a 1mg vial. That gives you 1,000mcg per mL. For a 20mcg dose, draw 2 units on a U-100 insulin syringe. For 50mcg, draw 5 units. Swirl gently. Never shake. Refrigerate after reconstitution. Use within 3-4 weeks. IGF-1 LR3 is fragile. Keep cold.
Evidence
Early research. IGF-1 LR3 is a modified version of insulin-like growth factor 1 with a longer half-life (~20-30 hours vs ~15 minutes for native IGF-1). Used primarily in bodybuilding for muscle hypertrophy. No completed human clinical trials. The mechanism is well-understood from IGF-1 biology but the modified version is research-grade only.
Approval status: Not approved
References
Tomas FM, Knowles SE, Owens PC, et al. Insulin-like growth factor-I (IGF-I) and especially IGF-I variants are anabolic in dexamethasone-treated rats. Biochem J, 1993. PMID 8507693
Francis GL, Ross M, Ballard FJ, et al. Novel recombinant fusion protein analogues of insulin-like growth factor (IGF)-I indicate the relative importance of IGF-binding protein and receptor binding for enhanced biological potency. J Mol Endocrinol, 1992. PMID 1384701
Philippou A, Halapas A, Maridaki M, et al. Type I insulin-like growth factor receptor signaling in skeletal muscle regeneration and hypertrophy. J Musculoskelet Neuronal Interact, 2007. PMID 18094500
Barton ER. The ABCs of IGF-I isoforms: impact on muscle hypertrophy and implications for repair. Appl Physiol Nutr Metab, 2006. PMID 17213878
Storage
Lyophilized: Freeze at -20C for long-term. IGF-1 LR3 is fragile. Keep frozen until ready to reconstitute.
Reconstituted: Refrigerate at 2-8C. Use within 3-4 weeks. Very fragile in solution.
Water: Bacteriostatic water, 1mL per 1mg vial. Some protocols use acetic acid for reconstitution.
Needle: 29-31 gauge, 0.5 inch for SubQ or IM
These statements have not been evaluated by the FDA. This content is for educational purposes only. Consult a healthcare professional before starting any protocol. vialprep sells injection supplies, not compounds.
This page is a community reference, not medical advice. Content reflects what users report, not clinical recommendations. Nothing here is approved for human use unless specifically noted. Always consult a healthcare professional before starting any protocol. vialprep sells injection supplies, not compounds.
