IGF-1 LR3

IGF-1 LR3 (Long R3 IGF-1) is a modified form of insulin-like growth factor 1. Two changes to the sequence mean it barely binds the natural carrier proteins (IGFBPs). As a result more free, active IGF-1 stays in circulation, and for much longer than with the natural molecule.

In research IGF-1 LR3 is common mainly as a reagent for cell culture. In humans there is no approval and only a thin data record.

IGF-1 mediates many of the anabolic effects otherwise credited to growth hormone: it promotes cell growth, protein building and the uptake of nutrients into the cell. Through the IGF-1 receptor it also acts on muscle and connective tissue.

The LR3 variant is interesting because the weak carrier-protein binding keeps it active longer than natural IGF-1. But that is exactly what makes it more potent and therefore more sensitive to dose.

• The IGF-1 LR3 vial (lyophilized powder, usually 1mg).
• Bacteriostatic water for mixing.
• U-100 insulin syringes.
• Alcohol swabs and a clean workspace.

Use the calculator above: pick the vial size (usually 1mg) and water amount, it shows concentration and units per dose on the U-100 syringe.

A 1mg vial with 1ml bacteriostatic water gives 1000mcg per ml. A 50mcg dose is then 5 units on the insulin syringe. Just add the water and let it dissolve.

Subcutaneous into the subcutaneous fat, with the short insulin needle.

• Disinfect the site, pinch a skin fold, inject slowly.
• Rotate injection sites.
• Because IGF-1 acts insulin-like, watch for low-blood-sugar signs and do not overdose while fasted.

An older, cleanly published study (Tomas, 1993) compared natural IGF-1 with the LR3 variant in rats. Result: both promoted weight gain and nitrogen retention, but LR3-IGF-1 was markedly more potent because of the weak carrier-protein binding.

That supports the mechanism but it is animal research. Modern human studies specifically on LR3 and muscle building in healthy people are missing, and no approval exists.

• Insulin-like action with a risk of low blood sugar (shaking, sweating, ravenous hunger), especially fasted.
• Local reactions at the injection site.
• Theoretical concern: IGF-1 promotes cell growth generally, which can be critical with pre-existing growths. Long-term human safety data are missing.

• Start low (around 20mcg) and watch closely.
• Keep fast carbs handy in case of low-blood-sugar signs.
• Limit cycles because of the fading receptor response.
• Banned in official competition.

Before mixing the powder is robust, normal room temperature (around 20 to 25 degrees) is fine, ideally kept in the dark. After mixing, keep in the fridge (2 to 8 degrees), do not freeze. It stays good there for at least 8 to 10 weeks with barely any loss of potency, in practice considerably longer. Swirl or shake to mix, both are fine.