IGF-1 LR3 — Research, Dosing & Price Guide

IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a modified version of IGF-1 with an arginine substitution at position 3 and a 13-amino-acid extension at the N-terminus. These modifications dramatically reduce binding to IGF-binding proteins (IGFBPs), increasing its bioavailability and half-life from ~15 minutes to 20–30 hours. It is the most potent anabolic peptide available for direct tissue growth.

IGF-1 LR3 binds directly to the IGF-1 receptor (IGF-1R) on target cells, bypassing the normal regulatory system of IGF-binding proteins that sequester and limit endogenous IGF-1 activity. Upon binding, it activates the PI3K/Akt/mTOR signaling cascade — the central anabolic pathway controlling protein synthesis, cell proliferation, and apoptosis inhibition. This leads to muscle hypertrophy through increased satellite cell activation and myoblast fusion, enhanced amino acid uptake, and accelerated protein synthesis. Unlike GH secretagogues that work upstream, IGF-1 LR3 acts directly at the tissue level, producing potent local and systemic growth effects. It also promotes glucose uptake independently of insulin (via GLUT4 translocation) and stimulates both hyperplasia (new cell formation) and hypertrophy (cell enlargement) in skeletal muscle — a distinction from most anabolic agents which primarily cause hypertrophy alone.

• Studies show IGF-1 LR3 has approximately 3x the potency of native IGF-1 due to reduced IGFBP binding (Growth Hormone & IGF Research)
• Research demonstrated IGF-1 LR3 increases muscle satellite cell proliferation by 65% in vitro compared to 20% for native IGF-1
• Animal studies showed local IGF-1 injection produced 15% hypertrophy in injected muscles within 2 weeks (Journal of Applied Physiology, 2004)
• IGF-1 LR3 promotes both hyperplasia and hypertrophy — one of the few anabolic agents capable of increasing muscle fiber number
• Studies in elderly subjects showed IGF-1 administration improved nitrogen balance, lean body mass, and functional capacity
• Research in burn patients demonstrated IGF-1 accelerated wound healing and reduced protein catabolism
• Preclinical cancer research has investigated both pro- and anti-tumor effects of IGF-1 signaling — context-dependent outcomes

• Systemic protocol: 20–60 mcg subcutaneous injection daily, split into 1–2 doses
• Post-workout protocol: 40–80 mcg subcutaneous injection immediately after training
• Site-specific (intramuscular): 20–40 mcg injected bilaterally into target muscle groups post-workout
• Cycle length: 4–6 weeks on, 4–6 weeks off (to prevent receptor desensitization and preserve insulin sensitivity)
• Start at 20 mcg/day and titrate up based on response and blood glucose monitoring
• Monitor blood glucose — IGF-1 LR3 can cause hypoglycemia, especially with concurrent insulin use
• Avoid combining with exogenous insulin without medical supervision
• Take with a carbohydrate-containing meal post-injection to mitigate hypoglycemia risk

Known Side Effects

• Hypoglycemia: the most significant acute risk — can be severe, especially in fasted states or combined with insulin
• Joint and muscle pain as tissues grow rapidly
• Jaw and extremity growth with chronic high-dose use (acromegaly-like effects)
• Organ growth (intestinal hypertrophy, cardiac hypertrophy) with prolonged use at high doses
• Water retention and edema
• Increased tumor growth risk — IGF-1R signaling promotes proliferation of both normal and malignant cells
• Headache and facial puffiness

Safety Profile

IGF-1 LR3 is a powerful growth factor with significant safety considerations. Unlike GH secretagogues, it directly activates growth pathways without physiological feedback regulation, creating genuine risks with misuse. Hypoglycemia is the most immediate danger and can be life-threatening — always have glucose available. Chronic use at high doses can produce acromegaloid features (enlarged jaw, hands, feet) and organ hypertrophy. The most serious long-term concern is cancer risk: epidemiological studies consistently link elevated IGF-1 levels with increased risk of colorectal, breast, and prostate cancer. While short-term therapeutic use at moderate doses may not meaningfully increase risk, this compound should never be used by those with a personal or strong family history of cancer. Contraindicated in active malignancy, diabetes (without careful medical oversight), pregnancy, and individuals under 25 (growth plate concerns). Strict cycling is essential.

Week 1: Increased muscle fullness and pumps during training. Possible mild hypoglycemia symptoms (shakiness, sweating) — managed with carbohydrate intake. Enhanced recovery. Week 2–3: Noticeable increases in muscle size and vascularity. Strength gains begin. Appetite may increase. Some joint discomfort possible as growth outpaces connective tissue adaptation. Weeks 4–6: Significant measurable increases in lean mass (2–5 lbs achievable with proper training and nutrition). Recovery between sessions is dramatically improved. Body composition shifts visibly. After cycling off, gains are well-retained if training and nutrition remain consistent, unlike water-retention-based gains from other compounds.

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