Long-acting insulin-like growth factor analogue researched for muscle hyperplasia and nutrient partitioning.
IGF-1 LR3 (Long R3 IGF-1) is a modified, long-acting version of insulin-like growth factor 1 — the powerful growth factor through which much of growth hormone's muscle-building effect is actually carried out. The modifications extend its half-life from minutes to many hours and reduce its binding to carrier proteins, leaving more of it active.
It is a potent anabolic signal: IGF-1 drives both hypertrophy (bigger muscle cells) and, notably, hyperplasia (potentially new muscle cells), along with nutrient partitioning. That potency is exactly why it is also one of the riskier peptides here.
Because it promotes growth in all tissue — wanted and unwanted — and can cause low blood sugar, it demands respect: short cycles, careful dosing, and an absolute contraindication for anyone with cancer risk.
Potently drives muscle growth and nutrient partitioning.
Strong mechanistic and preclinical basis; human aesthetic use is anecdotal
Improves muscle fullness and local recovery.
Widely reported anecdotally; manage blood-sugar risk
Shuttles nutrients toward muscle tissue.
Mechanistically supported
We rate every peptide honestly across four dimensions — and tell you what it's not.
Mostly preclinical (animal/in-vitro) evidence with a clear mechanism. Human effects are largely anecdotal.
Experienced users seeking a potent anabolic signal, fully aware of the risks
Use short cycles only. Keep fast carbs handy for hypoglycemia. Absolutely avoid with any cancer history.
Women are cautious candidates given potency and limited female data
High potency with real hypoglycemia and growth risks. Not for anyone with cancer risk. Avoid in pregnancy.
Potent growth factor; limited female data. Not for anyone with cancer risk.
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Absolutely contraindicated with any history of cancer or active tumors.
Can cause hypoglycemia — do not use without understanding blood-sugar risks.
Use short cycles; promotes growth of all tissue including unwanted.
Have fast-acting carbohydrates available to manage low blood sugar.
The effects most commonly reported with IGF-1 LR3, when they tend to show up, and how to manage them.
Often eases as you adjust; lower the dose if bothersome.
A carpal-tunnel-like effect from fluid shifts — reduce dose if it persists.
Plan meals around dosing; more pronounced with GHRP-6/GHRP-2.
Dose before bed; lower the dose if daytime grogginess occurs.
Monitor fasting glucose and HbA1c; especially relevant if pre-diabetic.
Individual responses vary. Stop and consult a clinician for severe, persistent, or unexpected reactions.
14 steps with photos, pro tips, and a dosing calculator.
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View Full GuidePepCompass provides educational information only. Nothing on this platform constitutes medical advice, diagnosis, or treatment. All content is for informational and research purposes only. Always consult a licensed healthcare provider before starting any peptide protocol. Individual results vary.