Growth Hormone (GH), GH Secretagogues & IGF Peptides: Evidence Based Guide

This guide is for education and research literacy. It does not replace medical care, diagnosis, or treatment decisions.

Intro

The growth hormone (GH) and insulin-like growth factor (IGF-1) system is one of the most discussed (and most misunderstood) areas in performance, body composition, and clinical endocrinology. You’ll see everything from prescription GH replacement and FDA-approved secretagogues to “research-only” peptides marketed with claims that go far beyond the available human evidence.

This guide maps the landscape in plain language: how the GH–IGF axis works, what each category of compound is designed to do, what outcomes have been demonstrated in peer-reviewed human studies, and what the key safety and quality considerations are. It is written to improve scientific literacy—not to provide medical advice, diagnose conditions, or recommend personal use. If you’re considering any GH/IGF-active therapy, consult a qualified clinician.

How to use this page: Start with the GH–IGF axis overview, then jump to GH therapy, secretagogues, or IGF-based therapies depending on what you’re researching. Each section links to supporting studies and/or regulatory references.

Table of Contents

1. The GH–IGF Axis
2. Categories at a Glance
3. Growth Hormone (GH) Therapy (Somatropin)
4. GH Secretagogues
   1. Tesamorelin (GHRH analog)
   2. Ibutamoren (MK-677) (GHSR agonist)
   3. CJC-1295 (DAC) (long-acting GHRH analog)
   4. Other “GH peptides” you may hear about
5. IGF Peptides
   1. Mecasermin (rhIGF-1)
   2. “Research IGF” peptides (e.g., LR3, DES)
6. Risk, Quality & Legal Considerations
7. References

The GH–IGF Axis (what these compounds affect)

Growth Hormone (GH) is released in pulses from the pituitary gland, regulated by hypothalamic signals (GHRH and somatostatin) and influenced by sleep, exercise, nutrition, and stress. A major downstream effect of GH is stimulating liver and tissue production of insulin-like growth factor-1 (IGF-1), which mediates many growth and anabolic signals.

Key concepts

• GH therapies provide GH directly (replacement in medically confirmed GH deficiency).
• GH secretagogues stimulate the body to release more GH (often via GHRH signaling or ghrelin/GHSR signaling).
• IGF therapies provide IGF-1 directly (replacement in specific, rare pediatric disorders).

2) Categories at a Glance

Growth Hormone Therapy (Somatropin): Where it fits

Who GH replacement is target for

In adults, GH replacement is generally reserved for confirmed adult growth hormone deficiency (AGHD), typically due to pituitary disease or its treatment, and usually requires stimulation testing for diagnosis. Evidence-based guidelines outline evaluation and treatment standards.

What human studies show

Randomized placebo-controlled studies in AGHD have demonstrated improvements in body composition and related outcomes over months of therapy (with adverse effects that require monitoring)

Commonly discussed risks/monitoring topics

• Fluid retention-related symptoms (edema, joint pain, carpal tunnel–type symptoms)
• Changes in glucose tolerance/insulin sensitivity (especially in at-risk individuals)
• Careful risk assessment in people with a history of malignancy (decision individualized)

Clinical guidance emphasizes individualized dosing/monitoring by qualified clinicians rather than “one-size-fits-all”

GH Secretagogues

Tesamorelin (GHRH analog) — strongest clinical footing among ‘GH peptides’

Tesamorelin is a synthetic GHRH analog that increases endogenous GH and IGF-1. It has been studied extensively in people with HIV-associated lipodystrophy. In a pivotal randomized, placebo-controlled trial, tesamorelin reduced visceral adipose tissue and increased IGF-1 compared with placebo.

FDA prescribing information details the approved indication and safety considerations (including contraindications/warnings and monitoring recommendations).

Evidence-backed takeaways

• Most consistent benefit: reduction in visceral adipose tissue in the studied HIV population.
• IGF-1 increases: expected downstream effect that can be clinically relevant for monitoring.

Ibutamoren (MK-677) — oral GH secretagogue

Ibutamoren is a ghrelin receptor (GHSR) agonist that increases GH secretion and IGF-1 levels. Human trials show robust endocrine effects, but translation to meaningful functional outcomes can be variable across populations.

What trials suggest

• In obese adult males, an 8-week randomized, double-blind, placebo-controlled study reported increased GH secretion, IGF-1, and fat-free mass with MK-677 vs placebo
• In healthy older adults, a randomized trial of an oral ghrelin mimetic (MK-677) reported increases in GH/IGF-1 and fat-free mass, with limited improvement in some clinical performance endpoints
• In older adults recovering from hip fracture, a randomized, double-blind study assessed functional performance and IGF-1 changes with MK-0677 (MK-677) vs placebo

Safety signals to understand

• Increased appetite (ghrelin-pathway effect)
• Fluid retention/edema in some users
• Potential worsening of insulin resistance/glucose control in susceptible individuals

Because MK-677 is not FDA-approved for anti-aging/body composition enhancement, risk–benefit decisions should be clinician-led when used in legitimate investigational settings. Public health agencies have also warned about risks when used outside medical oversight.

CJC-1295 (DAC) — long-acting GHRH analog studied in healthy subjects (investigational)

CJC-1295 (DAC) has been studied as a long-acting GHRH analog that produces prolonged elevations of GH and IGF-1 after administration in controlled settings.

Important: Clinical research on GHRH/GHSR agents does not automatically justify non-medical use. Human endocrine changes are not the same as proven long-term clinical benefit.

Other “GH peptides” you may hear about

Compounds like GHRP-class peptides and certain short GHRH fragments are widely discussed online, but the quality and accessibility of peer-reviewed human efficacy/safety data varies greatly by compound. When a compound lacks well-controlled human trials, treat claims as unproven.

IGF Peptides: What’s real, what’s hype

Mecasermin (rhIGF-1) — the only widely recognized prescription IGF-1 therapy

Mecasermin (recombinant human IGF-1) is indicated for pediatric patients with specific rare causes of severe growth failure (e.g., severe primary IGF-1 deficiency) under specialist care. Regulatory documents outline indication, dosing framework, and safety risks (notably hypoglycemia and tissue hypertrophy warnings).

Real-world registry analyses continue to report growth outcomes and safety observations in treated patients.

Research IGF peptides IGF-1 LR3, DES(1-3) IGF-1)

These peptides are most often encountered in laboratory research (cell culture and animal models) and in gray-market “research-only” sales. Unlike mecasermin (rhIGF-1), they are not FDA-approved drugs for general clinical use. The biggest gap: while their biochemical rationale is well-described, there is limited high-quality human clinical evidence supporting real-world outcomes or long-term safety when used outside regulated medical contexts.

What makes these “research IGF” analogs different from native IGF-1?

• They’re engineered to change binding to IGF-binding proteins (IGFBPs). In the body, IGFBPs regulate where IGF-1 travels, how long it lasts, and how much “free” IGF-1 is available to activate receptors. Altering IGFBP binding can change potency, duration, and tissue exposure.
• They often increase “effective exposure” at the IGF-1 receptor (IGF-1R) in experimental systems. That can be useful in controlled assays, but it also means they may not mirror normal physiology well.

IGF-1 LR3 (Long-[Arg3]-IGF-1): what the modifications do

IGF-1 LR3 (also called Long-[Arg3]-IGF-1) is an IGF-1 analog with an Arg substitution at position 3 and an N-terminal extension (commonly described as a 13-amino-acid extension in research reagents) designed to reduce interaction with IGFBPs and improve stability in experimental use.

• Reduced IGFBP binding is a central design feature. Reviews of IGFBP interactions note that the amino acid at position 3 is important for IGFBP binding, and Arg3 variants show reduced IGFBP interaction.
• Structural work supports that the engineered N-terminus behaves differently than native IGF-1, consistent with altered IGFBP affinity.
• Important reality check: LR3 is widely used as a tool in biology (e.g., stimulating IGF-1R signaling in cells). That is not the same as demonstrating safe, beneficial outcomes in humans.

Human clinical evidence status: You can find peer-reviewed work on detecting/quantifying IGF-1 analogs (including LongR3-IGF-I and Des(1-3)IGF-I) in human plasma for analytical and anti-doping contexts—this supports that these analogs are measurable and distinguishable, not that they’re proven for wellness/performance use.

DES(1-3) IGF-1 (Des(1-3)IGF-I): why it’s considered “more potent” in many assays

DES(1-3) IGF-1 is a naturally occurring truncated form/analog of IGF-1 lacking the first three amino acids at the N-terminus. The literature commonly describes it as having much lower IGFBP binding, which can translate into greater apparent potency in vitro and in some in vivo models.

• A classic review describes DES(1-3)IGF-I as often ~10× more potent than IGF-I for stimulating proliferation/hypertrophy in cultured cells, largely due to reduced IGFBP binding.
• Experimental endocrine literature also shows DES(1-3)IGF-I can exert stronger effects than IGF-I in specific cell systems (example: Hep G2 model effects on IGFBP-1 output), illustrating how analogs can behave differently than native IGF-1 under controlled conditions.

Human clinical evidence status: Like LR3, DES(1-3)IGF-I appears more often in mechanistic/experimental work than in robust therapeutic trials for general use. If a claim hinges on body recomposition, athletic performance, or “anti-aging,” it typically exceeds what controlled human outcomes data can confidently support.

Why “research IGF” peptides can be higher-risk than people assume

• IGF signaling is growth/mitogenic biology. IGF-1R activation drives pathways tied to cell growth and proliferation—useful in research, but it also means exposure is not trivial from a risk perspective (especially long-term or supraphysiologic exposure).
• Metabolic risk: IGF-1 has insulin-like activity; clinically used rhIGF-1 (mecasermin) carries a well-known hypoglycemia risk in labeling, underscoring that IGF activity can meaningfully affect glucose physiology. (See the mecasermin section/label in your References list.)
• Quality/identity risk: Outside pharmacy-grade manufacturing, identity, purity, endotoxin burden, and dosing accuracy can be uncertain.
• Detection in sport: Analytical studies focus on detecting IGF analogs/metabolites in human samples, reflecting anti-doping and forensic interest.

Evidence-based bottom line

• What’s solid: These analogs have a clear mechanistic rationale (notably altered IGFBP binding) and are well-used in experimental biology.
• What’s not solid: Broad claims about predictable muscle gain, recovery, or longevity benefits in humans—especially long-term—are not backed by the same depth of controlled clinical outcomes data as approved therapies.

Risk, Quality & Legal Considerations

• Medical oversight matters: These are endocrine-active agents with systemic effects.
• Product quality: Non-pharmacy supply chains add contamination/dosing uncertainty risk.
• Sport rules: Many GH-axis agents are prohibited in tested sport (check your governing body).
• Contraindications: Pregnancy, active malignancy, and uncontrolled diabetes are common “red flag” contexts for GH/IGF-axis manipulation (clinical decisions are individualized).

Related articles

• Metabolic peptides
• Recovery & repair
• Cellular longevity
• Storage and Reconstitution

Related products

• CJC1295
• CJC 1295 (No DAC)
• CJC/IPA blend
• Ipamorelin
• Tesamorelin
• IGF-LR3

References

Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Vance ML. Evaluation and Treatment of Adult Growth Hormone Deficiency: An Endocrine Society Clinical Practice Guideline. JCEM (2011).
https://academic.oup.com/jcem/article/96/6/1587/2833853

AACE — Clinical Practice Guideline: Management of Growth Hormone Deficiency in Adults (2019)
https://pro.aace.com/clinical-guidance/2019-clinical-practice-guideline-management-growth-hormone-deficiency-adults

Hoffman AR, et al. Growth Hormone (GH) Replacement Therapy in Adult-Onset GH Deficiency: Effects on Body Composition in Men and Women in a Double-Blind, Randomized, Placebo-Controlled Trial. JCEM (2004).
https://academic.oup.com/jcem/article-abstract/89/5/2048/2844165

Falutz J, et al. Metabolic Effects of a Growth Hormone–Releasing Factor in Patients with HIV. NEJM (2007).
https://www.nejm.org/doi/pdf/10.1056/NEJMoa072375

FDA — EGRIFTA SV (tesamorelin) Prescribing Information (2 mg/vial) (2019).
https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/022505Orig1s010lbl.pdf

FDA — EGRIFTA WR (tesamorelin) Prescribing Information (label, 2025).
https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/022505s020lbl.pdf

Stanley TL, et al. Effect of Tesamorelin on Visceral Fat and Liver Fat in HIV-Infected Patients with Abdominal Fat Accumulation. JAMA (2014).
https://jamanetwork.com/journals/jama/fullarticle/1889139

(Systematic review/meta-analysis) Body composition, hepatic fat, metabolic, and safety outcomes of tesamorelin in adults with HIV: systematic review and meta-analysis (search through July 2025). (2026).
https://www.sciencedirect.com/science/article/pii/S1871403X26000025

Teichman SL, et al. Prolonged Stimulation of Growth Hormone (GH) and Insulin-Like Growth Factor-I Secretion by CJC-1295, a Long-Acting Analog of GH-Releasing Hormone, in Healthy Adults. JCEM (2006).
https://academic.oup.com/jcem/article-abstract/91/3/799/2843281

Svensson J, et al. Two-Month Treatment of Obese Subjects with the Oral Growth Hormone (GH) Secretagogue MK-677 Increases GH Secretion, Fat-Free Mass, and Energy Expenditure. JCEM (1998).
https://academic.oup.com/jcem/article-abstract/83/2/362/2865156

MK-677, an Orally Active Growth Hormone Secretagogue, Reverses Diet-Induced Protein Catabolism. JCEM (1998).
https://academic.oup.com/jcem/article-abstract/83/2/320/2865101

Nass R, et al. Effects of an Oral Ghrelin Mimetic on Body Composition and Clinical Outcomes in Healthy Older Adults: A Randomized Trial. Ann Intern Med (2008) (free full text via Europe PMC).
https://europepmc.org/article/pmc/2757071

Adunsky A, et al. MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. Arch Gerontol Geriatr (2011) (
https://www.sciencedirect.com/science/article/pii/S0167494310002530

Baxter RC. Insulin-like growth factor (IGF)-binding proteins: interactions with IGFs and intrinsic bioactivities. Am J Physiol Endocrinol Metab (2000)
https://journals.physiology.org/doi/pdf/10.1152/ajpendo.2000.278.6.e967

Probing the Folding Pathways of Long R3 Insulin-like Growth Factor-I (LR3IGF-I). J Biol Chem 
https://www.jbc.org/article/S0021-9258%2819%2952934-9/fulltext

Sara VR, Hall K. Des(1–3)IGF-I: a truncated form of insulin-like growth factor-I. Int J Biochem Cell Biol (1996)
https://www.sciencedirect.com/science/article/pii/1357272596000568

Lindgren BF, et al. Insulin-like growth factor binding protein-1 from Hep G2 cells is potently inhibited by des(1–3) IGF-I.Eur J Endocrinol (1993).
https://academic.oup.com/ejendo/article/128/1/81/6769547

Thomas A, et al. Determination of LongR3-IGF-I, R3-IGF-I, Des1-3 IGF-I and their metabolites in human plasma samples by LC-MS. Growth Hormone & IGF Research (2017)
https://www.sciencedirect.com/science/article/pii/S1096637417300540