IGF-1
Insulin-like Growth Factor 1 — the 70-amino-acid peptide hormone that serves as the primary mediator of growth hormone's anabolic effects throughout the body. Produced mainly by the liver in response to GH signaling, IGF-1 drives protein synthesis, cell proliferation, and tissue growth. FDA-approved as Increlex for primary IGF-1 deficiency, with off-label use in bodybuilding and anti-aging for its potent anabolic and recovery-enhancing properties.
Dosage
| Weight | Suggested Dose |
|---|---|
| 60 kg / 130 lbs | 20-60 mcg subcutaneous 1-2x daily with food |
| 75 kg / 165 lbs | 30-80 mcg subcutaneous 1-2x daily with food |
| 90 kg / 200 lbs | 40-100 mcg subcutaneous 1-2x daily with food |
| 115 kg / 250 lbs | 50-120 mcg subcutaneous 1-2x daily with food |
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Administration
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Effects
Anabolic
Primary mediator of GH's effects — drives protein synthesis and tissue growth.
Recovery
Promotes muscle repair, bone formation, and neuronal survival.
Mechanism of Action
IGF-1 (Insulin-like Growth Factor 1) is a 70-amino-acid peptide hormone with approximately 50% structural homology to proinsulin. It is primarily produced by hepatocytes in response to growth hormone stimulation, though virtually all tissues produce IGF-1 locally for paracrine/autocrine signaling. Circulating IGF-1 is bound to six IGF binding proteins (IGFBP-1 through IGFBP-6), with approximately 80-90% bound to IGFBP-3 in a ternary complex with the acid-labile subunit (ALS). Only free, unbound IGF-1 (approximately 1-2% of total) can activate receptors.
IGF-1 binds to the IGF-1 receptor (IGF-1R), a heterotetrameric receptor tyrosine kinase structurally similar to the insulin receptor. Ligand binding triggers receptor autophosphorylation and recruitment of insulin receptor substrate (IRS) adaptor proteins, activating two major downstream cascades. The PI3K/Akt/mTOR pathway drives protein synthesis (through mTORC1 activation of S6K1 and inhibition of 4E-BP1), cell survival (through BAD phosphorylation and Bcl-2 family regulation), and glucose uptake (through GLUT4 translocation). The Ras/Raf/MEK/ERK pathway promotes cell proliferation, differentiation, and gene expression changes required for tissue growth.
In skeletal muscle, IGF-1's effects include both hypertrophy (enlargement of existing muscle fibers through increased protein synthesis) and hyperplasia (generation of new muscle cells through satellite cell activation and differentiation). Local muscle-derived IGF-1 isoforms (including the MGF splice variant) play a particularly important role in exercise-induced muscle adaptation. The very short half-life of free IGF-1 (10-20 minutes) means that therapeutic administration requires frequent dosing or modified forms (such as IGF-1 LR3 with its extended half-life). Native IGF-1 also binds the insulin receptor (with lower affinity), which contributes to its hypoglycemic effects — a significant clinical risk that requires careful glucose monitoring and administration with food.
Regulatory Status
FDA approved as Mecasermin (Increlex) for severe primary IGF-1 deficiency. Off-label use is common in anti-aging and bodybuilding. Controlled in many sports organizations.
Risks & Safety
Common
low blood sugar (significant risk — must eat with dosing), joint pain, headache, injection site reactions.
Serious
may promote existing tumors, organ enlargement (intestines, heart) with long-term use, jaw and extremity growth.
Rare
increased pressure in the skull, tonsil enlargement, allergic reactions. Requires blood glucose monitoring.
Compare IGF-1 With
Research Papers
31Published: February 24, 2026
AI Summary
Heparin-modified collagen scaffolds outperform other glycosaminoglycan types at promoting muscle cell growth and differentiation in lab-grown tissue. Because they trap and hold more IGF-1, these scaffolds could improve skeletal muscle engineering and repair.
Published: September 10, 2026
AI Summary
Removing a large abdominal solitary fibrous tumor cured a patient whose low blood sugar had not responded to other treatments. The case shows that surgery can resolve tumor-driven hypoglycemia when standard therapies fail.
Published: February 1, 2026
AI Summary
People with psoriasis showed different IGF-related blood markers than healthy controls, with higher glucose, insulin, and some binding proteins and lower IGF-1. These findings link IGF signaling to both psoriasis and its metabolic complications like diabetes and insulin resistance.
Published: January 15, 2025
AI Summary
Researchers examined how IGF-1 influences an enzyme linked to insulin resistance and heart disease in obese rats. The work explores whether IGF-1 could help protect heart health in obesity by modulating this pathway.
Published: January 14, 2025
AI Summary
When standard hormone-blocking drugs failed to prepare a patient for pituitary tumor surgery, Lugol's solution successfully stabilized their thyroid levels. The case suggests Lugol's may be a useful backup option for rare tumors that do not respond to usual treatments.
Published: January 29, 2026
AI Summary
A machine learning model successfully predicted which glaucoma patients would respond to eye pressure–lowering drugs. Blood levels of IGF-1 and LDL cholesterol emerged as the strongest predictors, suggesting these factors may influence treatment outcomes.
Published: February 1, 2026
AI Summary
Among several cancer drugs tested, only cisplatin triggered muscle wasting in mice by activating cellular stress and protein breakdown pathways. Blocking these stress pathways could help prevent chemotherapy-related muscle loss.
Published: January 30, 2026
AI Summary
A network meta-analysis compared how different treatments affect blood markers linked to age-related muscle loss. The work helps identify which interventions may best improve these factors in people with sarcopenia.
Published: February 9, 2026
AI Summary
Sun-weathered microplastics sped up aging in worms more than fresh microplastics by disrupting insulin signaling and triggering iron-dependent cell death. The results point to greater health risks from aged plastic pollution in the environment.
Published: February 3, 2026
AI Summary
Researchers evaluated the long-term effectiveness and safety of once-weekly somapacitan in short children born small for gestational age, including those who switched from daily growth hormone. The abstract reports study aims rather than specific findings.
Published: January 28, 2026
AI Summary
Researchers used FDA reports to build a clearer picture of side effects linked to vosoritide, a dwarfism drug. The work fills a gap in safety data needed for informed clinical use.
Published: January 11, 2025
AI Summary
Dopamine appears to influence growth hormone release, but exactly how and through which cells remains unclear. The paper reviews what is known and identifies gaps in understanding this regulatory pathway.
Published: January 6, 2026
AI Summary
Nanofibers that carry both FGF2 and IGF1 boosted nerve cell growth better than either factor alone or the scaffold by itself. These materials could support nerve repair and tissue regeneration.
Published: March 22, 2026
AI Summary
Immune cell–derived vesicles ferry IGF-1 and FGF-2 between muscle and bone, shaping how bone is built and broken down. This review explains how different macrophage types tip the balance toward bone loss or repair.
Published: January 5, 2026
AI Summary
In lactating rats, fish oil improved milk quality and breast tissue function more than flaxseed or walnut oil. Fish oil may be the most effective omega-3 source for supporting nursing mothers and infant nutrition.
Published: January 19, 2026
AI Summary
Researchers examined how 35 days of liraglutide affected body composition and blood markers of muscle and bone metabolism. The work clarifies the drug’s early effects beyond weight loss.
Published: February 19, 2026
AI Summary
Researchers analyzed whether pituitary hormone levels in patients with pituitary tumors relate to obstructive sleep apnea severity. The work explores how hormone imbalances might influence breathing during sleep.
Published: December 31, 2025
AI Summary
The study tested whether poor diet and low activity raise IGF-1 levels and breast cancer risk in Palestinian women. The abstract describes the hypothesis and design; results would show if lifestyle changes could lower risk.
Published: September 20, 2025
AI Summary
Researchers investigated how IGF-1 and its receptor change in bipolar mania and in response to olanzapine treatment. The work explores whether growth factor signaling contributes to the disorder or its treatment.
Published: January 20, 2026
AI Summary
Aggressive liposarcoma cells lose IGF-1 signaling and a key fat-cell regulator, which blocks normal differentiation and worsens survival. Restoring that regulator reversed the defect, and the cells’ reliance on the IGF-1 receptor points to a possible drug target.
Published: February 24, 2026
AI Summary
Abnormal RNA methylation in the uterine lining lowers IGF-1 and disrupts the tissue changes needed for a healthy pregnancy, contributing to preeclampsia. The findings suggest new targets for diagnosis and treatment of this pregnancy complication.
Published: January 4, 2025
AI Summary
Researchers tested whether Morinda officinalis oligosaccharides improve sperm movement in mice with chemically induced poor sperm motility. The abstract describes the study aims; results would clarify whether gut bacteria and IGF-1 signaling are involved.
Published: February 2, 2026
AI Summary
A new sensor using light-driven liquid metal and DNA detected IGF-1 with high sensitivity across three readout modes. The approach could support earlier disease detection and monitoring.
Published: February 15, 2026
AI Summary
Researchers explored whether muscle-derived signaling molecules like IGF-1 and irisin help explain the link between muscle loss and cognitive decline in older adults. The work could clarify how physical frailty and brain health are connected.
Published: January 26, 2026
AI Summary
Tumor-supporting cells release vesicles carrying a protein that suppresses IGFBP3 and amplifies IGF-1 signaling, driving lung cancer spread. Blocking this pathway could offer a new way to slow metastasis.
Published: January 15, 2026
AI Summary
A meta-analysis evaluated tesamorelin for HIV-associated lipodystrophy, a condition marked by belly fat buildup and metabolic problems. The abstract describes the study aim; full results would show effects on body composition, liver fat, and safety.
Published: January 10, 2026
AI Summary
Replacing some maltodextrin with galactose in young mice lowered body weight, fat, and energy use early on, and reduced liver IGF-1 expression later in female mice. The results raise questions about how lactose-free infant formulas affect long-term metabolism.
Published: April 11, 2026
AI Summary
IGF-1 protected nerve cells from arsenic-induced cell death and DNA damage by restoring a key survival pathway. The findings suggest IGF-1 signaling could be a target for treating arsenic-related brain injury.
Published: January 17, 2026
AI Summary
Adding FGF2, LIF, and IGF1 to pig egg maturation medium boosted embryo development and live births by improving communication between supporting cells and eggs. The work clarifies how these growth factors improve assisted reproduction in pigs.
Published: February 3, 2026
AI Summary
People with a genetic form of growth hormone deficiency in Brazil have very low IGF-1 but no early heart disease and normal lifespan. The paper reviews how enzymes that release IGF-1 from its binding proteins may explain this surprising resilience.
Published: April 14, 2026
AI Summary
A sugar from a Chinese medicinal plant extended lifespan and reduced aging-related decline in worms and mice by dampening insulin/IGF-1 signaling. The findings support exploration of this compound for anti-aging applications.
Frequently Asked Questions
What is IGF-1?
Insulin-like Growth Factor 1 — the 70-amino-acid peptide hormone that serves as the primary mediator of growth hormone's anabolic effects throughout the body. Produced mainly by the liver in response to GH signaling, IGF-1 drives protein synthesis, cell proliferation, and tissue growth. FDA-approved as Increlex for primary IGF-1 deficiency, with off-label use in bodybuilding and anti-aging for its potent anabolic and recovery-enhancing properties.
What is IGF-1 used for?
Insulin-like Growth Factor 1 — the 70-amino-acid peptide hormone that serves as the primary mediator of growth hormone's anabolic effects throughout the body. Produced mainly by the liver in response to GH signaling, IGF-1 drives protein synthesis, cell proliferation, and tissue growth. FDA-approved as Increlex for primary IGF-1 deficiency, with off-label use in bodybuilding and anti-aging for its potent anabolic and recovery-enhancing properties.
What is the dosage for IGF-1?
Clinical (Increlex): 40-120 mcg/kg subcutaneous twice daily. Bodybuilding: 20-100 mcg subcutaneous once or twice daily, often post-workout. Must be administered with food to prevent hypoglycemia. Cycle length 4-6 weeks.
What are the side effects of IGF-1?
Common: low blood sugar (significant risk — must eat with dosing), joint pain, headache, injection site reactions. Serious: may promote existing tumors, organ enlargement (intestines, heart) with long-term use, jaw and extremity growth. Rare: increased pressure in the skull, tonsil enlargement, allergic reactions. Requires blood glucose monitoring.
How does IGF-1 work?
IGF-1 (Insulin-like Growth Factor 1) is a 70-amino-acid peptide hormone with approximately 50% structural homology to proinsulin. It is primarily produced by hepatocytes in response to growth hormone stimulation, though virtually all tissues produce IGF-1 locally for paracrine/autocrine signaling. Circulating IGF-1 is bound to six IGF binding proteins (IGFBP-1 through IGFBP-6), with approximately 80-90% bound to IGFBP-3 in a ternary complex with the acid-labile subunit (ALS). Only free, unbound IGF-1 (approximately 1-2% of total) can activate receptors. IGF-1 binds to the IGF-1 receptor (IGF-1R), a heterotetrameric receptor tyrosine kinase structurally similar to the insulin receptor. Ligand binding triggers receptor autophosphorylation and recruitment of insulin receptor substrate (IRS) adaptor proteins, activating two major downstream cascades. The PI3K/Akt/mTOR pathway drives protein synthesis (through mTORC1 activation of S6K1 and inhibition of 4E-BP1), cell survival (through BAD phosphorylation and Bcl-2 family regulation), and glucose uptake (through GLUT4 translocation). The Ras/Raf/MEK/ERK pathway promotes cell proliferation, differentiation, and gene expression changes required for tissue growth. In skeletal muscle, IGF-1's effects include both hypertrophy (enlargement of existing muscle fibers through increased protein synthesis) and hyperplasia (generation of new muscle cells through satellite cell activation and differentiation). Local muscle-derived IGF-1 isoforms (including the MGF splice variant) play a particularly important role in exercise-induced muscle adaptation. The very short half-life of free IGF-1 (10-20 minutes) means that therapeutic administration requires frequent dosing or modified forms (such as IGF-1 LR3 with its extended half-life). Native IGF-1 also binds the insulin receptor (with lower affinity), which contributes to its hypoglycemic effects — a significant clinical risk that requires careful glucose monitoring and administration with food.
How is IGF-1 administered?
IGF-1 is administered via subcutaneous injection.
What is the half-life of IGF-1?
The half-life of IGF-1 is 10-20 minutes (unbound) | 12-15 hours (bound to IGFBP-3).
Is IGF-1 legal?
FDA approved as Mecasermin (Increlex) for severe primary IGF-1 deficiency. Off-label use is common in anti-aging and bodybuilding. Controlled in many sports organizations.
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