In plain English
IGF-1 is the growth factor your liver makes in response to growth hormone, and it drives much of growth hormone’s muscle-building effect. IGF-1 LR3 is a modified version that lasts far longer in the body. It is used mainly by experienced bodybuilders and athletes for muscle growth and recovery.
What it's used for
- Muscle growth and fullness
- Recovery from hard training
- Fat loss as part of body recomposition
Benefits
In animal and lab studies, IGF-1 LR3 has shown:
- Strong stimulation of muscle cell growth and protein building
- Activation of muscle stem (satellite) cells involved in repair
- Increased use of glucose and fat for energy
Users report fuller muscles, faster recovery and gains in lean mass over 4–6 week courses.
How it works
In simple terms: IGF-1 LR3 delivers the “build and repair” signal of growth hormone directly to muscle.
It binds the IGF-1 receptor on muscle and other cells, triggering growth and protein-building pathways. Two changes (an arginine swap at position 3 and a 13-amino-acid extension) stop it from being trapped by the proteins that normally bind IGF-1 in the blood, so it stays active much longer than natural IGF-1.
Development history
- 1990s: Created in Australia as a research tool for growing cells in the lab, where its long activity was valuable.
- 2000s onward: Adopted by bodybuilders for muscle growth.
Typical protocols
These ranges are what users commonly report. IGF-1 LR3 is considered an advanced peptide.
| Use | Dose | Frequency | Length |
|---|---|---|---|
| Muscle growth | 20–50 mcg | Once daily, often after training | 4–6 weeks, then a break |
| Higher range (experienced users) | Up to 80–100 mcg | Once daily | Short courses |
Users eat carbohydrates around the dose to avoid low blood sugar.
Cycling
Run for 4–6 weeks, then a break of similar length, since the IGF-1 receptor becomes less responsive with continuous use.
Administration options
- Subcutaneous injection: common.
- Intramuscular injection: some users inject into the trained muscle after workouts.
Reconstitution and dosing calculator
IGF-1 LR3 usually comes in 1 mg vials. It is traditionally mixed with dilute acetic acid (0.6%) for stability, though many users use bacteriostatic water. Doses are small, so a 0.3 mL syringe helps.
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Show the math
This tool does arithmetic only. It does not choose a dose or confirm that any substance is right for you. Double-check every result against your syringe and your clinician’s instructions.
Side effects and safety
- Low blood sugar is the main risk: shakiness, sweating, hunger or confusion after a dose. Users keep fast-acting carbohydrates on hand.
- Other reported effects: injection-site pain, headache, joint aches and water retention.
- Because IGF-1 drives cell growth, people with active cancer or a history of cancer should avoid it.
- Prohibited in competitive sport (WADA).
- Avoid during pregnancy and breastfeeding.
Common stacks
- CJC-1295 and ipamorelin: combined by users so that natural growth hormone and IGF-1 LR3 work together.
- BPC-157 and TB-500: combined for recovery.
Storage
Powder: refrigerate or freeze, dry and away from light.
After mixing: refrigerate at 2–8 °C and use within about 3–4 weeks.
Compare with
- IGF-1 DES: a shorter-acting form used locally after training.
- Growth hormone peptides (CJC-1295, ipamorelin): raise your own IGF-1 more gently.
- MGF / PEG-MGF: related growth factors linked to muscle repair.
Frequently asked questions
Is IGF-1 LR3 for beginners?
No. It is considered an advanced peptide because of its strong effects and the risk of low blood sugar.
Why eat carbohydrates with it?
It increases glucose uptake, so eating carbohydrates helps prevent low blood sugar.
Why mix it with acetic acid?
Dilute acetic acid keeps it stable in solution; many users use bacteriostatic water instead.
References
- Tomas FM, et al. Insulin-like growth factor (IGF)-I and especially IGF-I variants are anabolic in dexamethasone-treated rats. Biochem J. 1992;282(1):91-97.