Growth factor

IGF-1 LR3

A long-acting growth factor for serious muscle and recovery.

Emerging evidence

Overview

IGF-1 LR3 (Insulin-like Growth Factor-1 Long R3) is a modified version of the naturally occurring IGF-1 growth factor. The modification extends its half-life significantly compared to native IGF-1, meaning it stays active in the body longer and delivers a more sustained anabolic signal. Its mechanism is direct: it drives muscle cell growth and repair by activating the IGF-1 receptor, promoting protein synthesis and satellite cell recruitment. Primary goal is building muscle, with healing and recovery as a strong secondary aim. People who use IGF-1 LR3 are typically those focused on serious lean mass development and faster tissue repair from training. It is taken by subcutaneous injection, post-workout. The dose range is 20 to 50 mcg, given daily. Cycles run 4 to 6 weeks. Ipamorelin stacks well with it for complementary GH-axis support. There are two significant safety considerations. First, IGF-1 LR3 can lower blood sugar - this is a real and monitored risk, particularly around the post-workout injection window. Second, and critically, it carries a cancer contraindication: anyone with a history of cancer is excluded from use. IGF-1 is a proliferative growth factor, meaning it promotes cell growth, and that mechanism requires careful evaluation in anyone with a cancer history. IGF-1 LR3 is a research compound, not FDA-approved. Exact dosing is set with a licensed provider in the PepDepo network at consult.

At a glance

Route

SC injection

Dose

20-50 mcg

Frequency

Daily

Timing

Post-workout

Cycle

4-6 weeks

Combining

Stacks well with: Ipamorelin

Safety

Can lower blood sugar; strong proliferative effects mean cancer caution.

Regulatory: Research compound.

Not appropriate if: cancer-history.

Questions

What makes IGF-1 LR3 different from regular IGF-1?⌄

The 'LR3' modification extends the half-life of IGF-1, meaning it remains active in the body for longer than the native form. That translates to a more sustained anabolic signal per dose.

How does it work?⌄

It binds to IGF-1 receptors on muscle cells and drives growth and repair - promoting protein synthesis and activating muscle satellite cells. It is a direct growth factor, not a hormone-releasing signal.

How is it taken?⌄

Subcutaneous injection, post-workout, at a dose of 20 to 50 mcg daily. Cycles run 4 to 6 weeks. Exact dose is set at consult.

Who should NOT use IGF-1 LR3?⌄

Anyone with a history of cancer is excluded. IGF-1 is a proliferative growth factor and that mechanism requires clinical evaluation in anyone with a cancer background. This is a firm contraindication.

What are the blood sugar risks?⌄

IGF-1 LR3 can lower blood sugar, particularly around the post-workout injection. This is monitored and factored into protocol design, but it is a real consideration - especially for people with diabetes or hypoglycemia.

What goals does it address?⌄

Muscle building is the primary goal. Recovery is a strong secondary goal. It is used by people focused on serious lean mass development and faster repair from training.

Is it FDA-approved?⌄

No. IGF-1 LR3 is a research compound. All use is under clinician supervision.

Want a personalized protocol?

Exact dosing is set with a licensed provider in the PepDepo network. This page is education, not a prescription.

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Education only, not medical advice. Peptides discussed are for informational purposes and many are not FDA-approved. Eligibility, prescribing, compounding, and dispensing are handled by appropriately licensed entities. Exact protocols and dosing are set with a licensed provider in the PepDepo network at consult. Content is pending clinical review.