Long R3 insulin-like growth factor-1
IGF-1 LR3
Cited range Hypoglycemia risk
What it is
IGF-1 LR3 is recombinant IGF-1 with an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. The changes reduce binding to IGF-binding proteins so more analog stays free and active in experimental systems.
Benefits in plain language
What researchers and reference users usually mean when they talk about this compound. These are study themes and common claims — not a promise that it will do this in you.
- This is a long-acting cousin of IGF-1, the growth factor that actually does a lot of GH’s muscle and tissue work.
- The hoped-for effect is more muscle protein building and nutrient shuttling into tissue.
- Because it stays around longer than natural IGF-1, hypoglycemia (feeling shaky/low sugar) is the practical risk people watch.
- This is a high-signal research compound, not a gentle secretagogue.
If a branded, FDA-approved product exists, that label is the only dose that is actually authorized. Research-chemical vials are a different object.
Mechanism of action
It activates the IGF-1 receptor (and can cross-talk with the insulin receptor), driving PI3K/Akt and MAPK pathways involved in growth, glucose uptake, and satellite-cell biology. That is also why hypoglycemia and theoretical tumor-growth concerns come up in every serious review.
Possible side effects / caveats
Most important practical risk discussed in research and sports-medicine reviews: low blood sugar. Other concerns: edema, jaw/joint ache from GH/IGF axis push, and the unresolved question of IGF signaling in existing malignancies. This is not a casual “recovery peptide.”
Protocol ranges
| Source tier | Amount | Frequency | Notes |
|---|---|---|---|
| Cited range | 20–50 mcg/day | Once daily in most secondary sources | Common research-community window |
| Cited upper talk | Up to ~100 mcg/day | Daily, short cycles | Higher figures appear; risk rises with dose |