IGF-1 LR3
Also known as Long R3 IGF-1, LR3 IGF-1
IGF-1 LR3 is a modified analog of insulin-like growth factor 1 in which an extra 13 amino acids are added to the B-chain and a single substitution reduces binding to IGF-binding proteins. This modification extends its circulating half-life far beyond native IGF-1, allowing more sustained receptor activation. Within the research and performance community, it is discussed primarily as a systemic anabolic agent believed to support muscle tissue growth and recovery. It is not an approved pharmaceutical product, and human clinical data specific to muscle-building outcomes are limited.
Reported benefits
- Reported support for lean tissue accrual when combined with resistance training
- Proposed enhancement of nutrient partitioning toward muscle over fat
- Suggested support for connective tissue and muscle recovery
- Extended systemic activity compared with native IGF-1 due to reduced clearance
How it works
IGF-1 LR3 binds the IGF-1 receptor, activating the PI3K/Akt/mTOR pathway that drives protein synthesis and cell growth, while reduced binding-protein affinity keeps more of the compound free and active in circulation. This prolonged receptor signaling is proposed to support satellite cell proliferation and nutrient uptake in skeletal muscle. Because IGF-1 receptors are expressed throughout the body, effects are not confined to muscle tissue alone.
Dosing ranges
| Tier | Dose | Frequency |
|---|---|---|
| Low | 20 mcg | once daily |
| Moderate | 40 mcg | once daily |
| High | 60 mcg | once daily |
Estimate your dose
Dose estimator
Educational estimate for IGF-1 LR3, scaled to body size. Not medical advice.
Read before using
This tool produces a rough, educational estimate by scaling commonly-published research ranges to lean body mass. It is not a prescription, medical advice, or a substitute for a licensed clinician. Most peptides use fixed dosing, not weight-based dosing. Individual needs vary. You are solely responsible for how you use this information.
Mixing & syringe units
Target dose follows the estimate above. Change it there, or edit it directly below.
Reconstitution calculator
How much water to add and how many insulin-syringe units to draw for IGF-1 LR3. Educational only.
Draw to this mark
0.8units
= 0.008 mL for a 40 mcg dose
Concentration
5,000 mcg/mL
Doses per vial
250
Under 2 units is hard to measure accurately. Use less water for a larger, easier-to-read draw.
A U-100 syringe reads 100 units per mL. This is a reconstitution math helper only, not a prescription or dosing advice. Verify every calculation and consult a qualified healthcare provider.
Possible side effects
Stacking notes
Frequently discussed alongside growth hormone secretagogues (e.g., GHRP/GHRH compounds) given the GH-IGF-1 axis relationship; combining with insulin or insulin-sensitizing agents raises hypoglycemia risk and warrants particular caution.
Common protocols
Common questions
What is IGF-1 LR3 used for?
IGF-1 LR3 is a modified analog of insulin-like growth factor 1 in which an extra 13 amino acids are added to the B-chain and a single substitution reduces binding to IGF-binding proteins. This modification extends its circulating half-life far beyond native IGF-1, allowing more sustained receptor activation. Within the research and performance community, it is discussed primarily as a systemic anabolic agent believed to support muscle tissue growth and recovery. It is not an approved pharmaceutical product, and human clinical data specific to muscle-building outcomes are limited. Reported benefits include reported support for lean tissue accrual when combined with resistance training, proposed enhancement of nutrient partitioning toward muscle over fat, suggested support for connective tissue and muscle recovery.
What is a typical IGF-1 LR3 dose?
Reported ranges run 20-60 mcg. A low protocol is 20 mcg once daily, and a high protocol is 60 mcg once daily. This is reference information, not a dosing recommendation.
What is the half life of IGF-1 LR3?
Approximately 20-30 hours. That is what sets the dosing frequency, and it is why the timing guidance is after a workout.
How is IGF-1 LR3 administered?
SubQ or IM: into fat or muscle. Often injected subcutaneously for a systemic effect, or intramuscularly into a trained muscle for a more localized effect.
How long is a IGF-1 LR3 cycle?
4-6 weeks on, followed by 4-6 weeks off. Extended systemic use is often cycled off to allow IGF-1 receptor sensitivity and endogenous signaling to normalize; protocols vary widely and are not standardized in clinical literature.
What are the side effects of IGF-1 LR3?
Reported side effects include hypoglycemia, particularly when combined with insulin or during fasted states, potential for organ growth (organomegaly) with prolonged high-dose use, injection site irritation, theoretical concern for promoting growth of existing abnormal or cancerous cells due to broad growth-factor activity. Evidence level for this compound is emerging research.
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Educational use only, not medical advice. This profile is provided for research and educational purposes. IGF-1 LR3 may be a research compound or a prescription medication; nothing here is intended to diagnose, treat, cure, or prevent any disease. Dosing figures reflect commonly-published research ranges, not a prescription. Consult a qualified healthcare provider before making any health decision. Read the full disclaimer →