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IGF-1 LR3

A long-acting form of the growth factor IGF-1, discussed for muscle.

StatusNot approved (research reagent); WADA prohibited
How well studied in peopleAnimal & lab only
Experts quoted3 experts

iNot medical advice. We don’t recommend any dose. Every dose below is a quote from the person named, describing their views or their own use. IGF-1 LR3 is a laboratory reagent, not a medicine. It is not approved for human use in the EU, UK or US and is prohibited by WADA.

What experts say about dosing

6 statements from 3 people. Each one is word for word: we add punctuation only and mark cuts with […]. The chips repeat the exact words used.

Vigorous SteveBodybuilding coach and YouTuber (VigorousSteve)

Dose range and cycle

Dose
“anywhere between 50 micrograms bilaterally up to 500 micrograms bilaterally”
How often
“per day”
How long
“up to 21 days and then one week off”
Also said
“if your source is great”

“I think i1 lr3 is great if your source is great, right. Ideal dose is anywhere between 50 micrograms bilaterally up to 500 micrograms bilaterally […] it's 500 micrograms per side, okay, so 1 milligram per day, uh, up to 21 days and then one week off”

Watch at 1:19:23IGF-1-LR3 Protocols, High-Dose Test… (VigorousSteve Q&A, 23 Dec 2023) · 23 Dec 2023

Context: Answering a viewer question in a solo Q&A livestream. “i1 lr3” is how the auto-captions render IGF-1 LR3. The cut removes him correcting himself out loud (including a profanity) about milligrams versus grams.

Typical range, route and timing

Dose
“250 micrograms to 500 micrograms bilaterally”
How long
“21 days on and 7 to 10 days off”
How taken
“intramuscular”
Where
“into the muscle group that you're going to train”

“you find out your sweet spot. For most people that's like 250 micrograms to 500 micrograms bilaterally, so that's double the dose obviously because you do two administrations. You do intramuscular administrations into the muscle group that you're going to train, um, and then you run that for 21 days […] 21 days on and 7 to 10 days off”

Watch at 1:19:55IGF-1-LR3 Protocols, High-Dose Test… (VigorousSteve Q&A, 23 Dec 2023) · 23 Dec 2023

Context: Continuation of the same answer. The cut removes a self-correction (“off 7 to 10 days or”).

Bulking vs cutting

Dose
“maybe 100 micrograms … bilaterally during a bulking phase and up to 250 mics … bilaterally on a cutting phase”

“if I didn't have access to incx then I would run maybe 100 micrograms i1 lr3 bilaterally during a bulking phase and up to 250 mics […] lr3 bilaterally on a cutting phase”

Watch at 18:15IGF-1 LR3 Timing, High-Dose GH… (VigorousSteve Q&A, 6 Jul 2024) · 6 Jul 2024

Context: Solo Q&A. He says he uses prescription IGF-1 (Increlex, captioned “incx”) himself; this is what he says he would use otherwise. The cut removes two garbled words in the captions (“I just W”), flagged for a listen.

Ben GreenfieldFitness and longevity author; host of Ben Greenfield Life

Timing

Dose
“50–150mcg”
How often
“1x/day”
How long
“for a 4-week cycle”
How taken
“subcutaneous injection”
When
“preferably pre-workout or with your first-morning meal”

“Dosing guidelines are 50–150mcg 1x/day for a 4-week cycle, usually via subcutaneous injection, preferably pre-workout or with your first-morning meal.”

Read the sourceSafe Ozempic Alternatives: Peptides for Weight Loss & Muscle Gain (bengreenfieldlife.com) · 21 May 2024

Context: From an article on his own site about peptides for weight loss and muscle gain (first published 21 May 2024, updated 20 Apr 2026).

Muscle gain/fat-loss stack (dosing guidelines)

Dose
“50–150mcg”
How often
“1x/day”
How long
“for a 4-week cycle”
How taken
“Subcutaneous injection”

“Dosing Guidelines: 50–150mcg 1x/day for a 4-week cycle; OR 4mL of 620mcg/mL solution 1x/day. Administration Route: Subcutaneous injection”

Read the sourceBen’s Peptide Stack for Recovery, Explosive Gains, & Ageless Vitality (bengreenfieldlife.com) · 17 Sep 2024

Context: Published as “Dosing Guidelines” in the muscle gain/fat-loss (“Lean and Mean”) stack on his own site; not described as his own use. Bullet points joined into one line.

Nicholas TrigiliHuman performance specialist and coach; fitness YouTuber

Pre-workout use (“not for beginners”)

Dose
“100 to 200 micrograms”
How often
“training four or five times a week … one or two days off”
How long
“blasts (six to eight weeks)”
When
“30 minutes to 45 minutes pre-workout”
Also said
“make sure you're monitoring your glucose levels”

“My favorite protocol, or I should say uses of IGF-1, would be typically around your workout. I like 30 minutes to 45 minutes pre-workout on your weight training day. Specifically, anywhere between 100 to 200 micrograms depending on where people's, let's say, IGF levels are or how they feeling, right? Could vary. And as far as the frequency goes, let's say you're training four or five times a week. That's fine. Definitely have one or two days off of IGF-1, but make sure you're monitoring your glucose levels because, well, hypoglycemia is real on this.”

Watch at 9:17The Only 3 Muscle Building Peptide Stacks For 2026 (Beginners Guide) (Nicholas Trigili) · 21 Feb 2026

Context: From the IGF-1 LR3 chapter (“This is not for beginners at all”); he describes “blasts” of about six to eight weeks. He says in his videos that he is not a doctor.

What experts say about safety

0 statements from 0 people about risks and how strong the evidence is.

No expert safety statements are listed yet.

Go deeper

What the research used

Context, not a dosing guide. IGF-1 LR3 was developed for cell culture. The only in-vivo data we found are from animal studies, and doping-control labs have found impure products on the black market. Nothing here establishes a human dose.

Animal studies

StudyStudied inWhat the study usedWhat it found
Tomas et al., 1993, Biochem JPubMed 7683875Diabetic ratsIGF-I and two more potent variants (including LR3) by continuous infusion for 7 daysVariants were 2.5–3 times more potent than IGF-I at restoring growth; muscle protein synthesis up to 50% higher

Product quality

StudyStudied inWhat the study usedWhat it found
Kohler et al., 2010, Growth Horm IGF ResPubMed 20675162Black-market product seized by doping controlMass-spectrometry analysisIdentified Long-R3-IGF-I with a His-tag left over from synthesis; effects in humans unknown
What we don’t know yet
  • No human trials of IGF-1 LR3.
  • IGF-1 can lower blood glucose; this is a known risk of IGF-1 drugs.
  • Raised IGF-1 is a theoretical concern for people with existing tumours.
  • Grey-market products are unregulated, so identity, purity and dose accuracy vary.
  • WADA prohibits IGF-1 and its analogues.
Common questions

Is IGF-1 LR3 the same as the medicine Increlex?

No. Increlex (mecasermin) is recombinant human IGF-1, approved for severe primary IGF-1 deficiency. IGF-1 LR3 is a modified, longer-acting analogue sold as a research reagent.

Why do the quotes say “bilaterally”?

Vigorous Steve describes splitting the dose between two sides of the body (into the muscle being trained). That is his wording, not ours.

Is IGF-1 LR3 allowed in sport?

No. WADA prohibits IGF-1 and its analogues.

Why does the protocol section only contain quotes?

We do not write our own dose ranges. The protocol cards show, word for word, what named people have publicly said, with their caveats and a link to the source.

About this page

Word-for-word statements about how IGF-1 LR3 is used in bodybuilding, each with a link to the source. The published research is listed separately as context.

Also known as
Long R3 IGF-1; LR3-IGF-1
Type
Synthetic long-acting IGF-1 analogue (83 amino acids)
Last updated
11 Oct 2026

Last reviewed 11 Oct 2026 · Compiled by the Peptide Dosing editorial team · How we check quotes