Supplement Scholar
Anabolic / Growth Factor

IGF-1 LR3

Research compound. This is not a dietary supplement. Unless it is identified as an approved prescription drug, it is not approved by the FDA for human use. This page summarizes published research for education only; we do not sell it or link to sellers.

IGF-1 LR3. Long-acting IGF-1 analog that resists IGFBP binding for sustained anabolic signaling.

How it works. Binds IGF-1R on muscle, bone, and other tissues, driving PI3K-Akt-mTOR signaling for protein synthesis, hyperplasia, and glucose uptake.

What the research supports. 2 graded claims. Strongest: Marked anabolic signaling (preclinical).

Hormonal impact. Effects on IGF-1 activity, Growth hormone, Insulin sensitivity, Thyroid axis.

Side effects and interactions. 1 medication interaction listed. Serious: Cardiac hypertrophy with long-term abuse.

Stacking. Pairs well with Adequate carbohydrate around dosing. Avoid combining with Active malignancy.

Common forms. Available as Subcutaneous injection.

Community. Experiences from people who have tried IGF-1 LR3. Anecdotes are not medical advice.

IGF-1 LR3. Long-acting IGF-1 analog that resists IGFBP binding for sustained anabolic signaling.

No single structure

What it is

IGF-1 LR3 is a recombinant IGF-1 variant with an arginine substitution and an N-terminal extension that reduces binding to IGFBP-3, dramatically extending its half-life and free-fraction activity.

Also called

Long R3 IGF-1

How it works

Binds IGF-1R on muscle, bone, and other tissues, driving PI3K-Akt-mTOR signaling for protein synthesis, hyperplasia, and glucose uptake.

Pathways

  • IGF-1R then PI3K then Akt then mTOR
  • GLUT4 translocation

Effects

  • ↑Protein synthesis and satellite-cell activation increases
  • ↑Peripheral glucose uptake increases
  • ↓Endogenous GH decreases

What the research supports

Marked anabolic signalingpreclinical
Potential support for tissue repairpreclinical

Strong: consistent results across large trials or meta-analyses. Moderate: several trials, mostly positive. Limited: small or mixed studies. Preclinical: animal or cell research only.

Hormonal impact

↑IGF-1 activityincreases
↓Growth hormonedecreases
~Insulin sensitivitymodulates
~Thyroid axismodulates

Side effects & interactions

Common side effects

  • Hypoglycemia
  • Injection-site soreness
  • Lethargy

Serious

  • Cardiac hypertrophy with long-term abuse
  • Tumor-growth concerns

Medication interactions

Insulinsevere

Compounded hypoglycemia risk.

Check any supplement–medication combination with your pharmacist before starting.

Combines with

Pairs well

  • Adequate carbohydrate around dosingBlunts hypoglycemia risk.

Avoid combining

  • Active malignancyIGF-1R activation may drive tumor growth.

Common forms

  • Subcutaneous injection

Discussion

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