Peptide profile
Frag 17-23
Experimental GH fragment targeting fat metabolism · also known as HGH Fragment 17-23, GH Frag 17-23, Growth Hormone Fragment 17-23
Compare Frag 17-23 with other peptides →Summary
Frag 17-23 is a short synthetic peptide fragment derived from amino acids 17 through 23 of the human growth hormone (hGH) sequence. It is hypothesized to retain lipolytic properties similar to larger hGH fragments while being structurally distinct from the more widely studied Frag 176-191. Evidence for its efficacy in humans remains largely anecdotal, with minimal published research specific to this fragment.
- Typical dose
- 250–500 mcg/day
- Half-life
- ~1–2 hours (estimated)
- Route
- Subcutaneous
- Cycle length
- 4–8 weeks
Mechanism
How it works
Frag 17-23 is proposed to interact with adipocyte signaling pathways in a manner analogous to other growth hormone-derived fragments, potentially stimulating lipolysis by modulating beta-adrenergic or cAMP-dependent pathways without significantly activating the full IGF-1 axis. The peptide is thought to mimic a region of hGH responsible for fat-mobilizing activity, triggering the breakdown of stored triglycerides into free fatty acids. However, specific receptor binding data and robust mechanistic studies for this particular fragment are not well established in the peer-reviewed literature.
Reported in research
Benefits
- Potential stimulation of lipolysis and mobilization of stored body fat
- May support improved body composition when combined with caloric deficit and exercise
- Theoretically avoids IGF-1-mediated side effects associated with full-length growth hormone
- Anecdotally reported to have a favorable tolerability profile at research doses
Context, not a prescription
Dosing
- Typical range
- 250–500 mcg/day (Subcutaneous)
- Cycle length
- 4–8 weeks
- Half-life
- ~1–2 hours (estimated)
Safety
Side effects & contraindications
Possible side effects
- Mild injection site redness or irritation
- Transient fatigue or lightheadedness
- Possible water retention at higher doses
- Mild headache reported anecdotally
Contraindications
- Active malignancy or history of cancer (theoretical growth-signaling concern)
- Pregnancy or breastfeeding
- Known hypersensitivity to any component of the formulation
- Severe hepatic or renal impairment
Research information, not medical advice. Always consult a licensed clinician before considering any peptide.
In depth
Full profile
What it does
Some users anecdotally report reduced body fat, particularly in stubborn areas, and a slight improvement in definition. These changes are subtle and depend heavily on diet and training.
How it works
Imagine growth hormone is a master key that opens many different doors in your body. Frag 17-23 is like a small copy of just one tooth on that key — it might still open the 'fat-burning door' without unlocking all the other doors that could cause side effects.
When administered under the skin, Frag 17-23 is thought to travel through the bloodstream to fat cells, where it may signal them to break down stored fat and release it as energy. Unlike full growth hormone, it theoretically does not strongly stimulate muscle growth or insulin-related pathways.
What to expect
Effects, if any, are typically not noticeable in the first week. Most users report subtle changes in body composition after 3–6 weeks of consistent use alongside diet and exercise.
- Week 1: Peptide is establishing baseline levels; no noticeable effects typically reported. Mild injection site reactions may occur as you adjust to the protocol.
- Weeks 2-4: Some users begin to notice very subtle changes in how their body responds to caloric restriction. Energy levels may feel slightly more stable, and some report minor improvements in definition.
- Weeks 4-8: Any meaningful changes in body composition would be expected in this window, primarily if accompanied by a caloric deficit and regular exercise. Results vary significantly between individuals.
Good to know
- Always reconstitute with bacteriostatic water and use sterile injection technique
- Start at the lower end of the dose range (250 mcg/day) and assess tolerance before increasing
Staying safe
- Mild redness or soreness at the injection site
- Occasional mild headache
Avoid if you have:
- People with a history of cancer
- Pregnant or breastfeeding individuals
- Anyone under 18 years of age
Mechanism of action
Frag 17-23 represents amino acids 17 through 23 of the 191-amino-acid human growth hormone sequence. Growth hormone exerts lipolytic effects partly through direct adipocyte receptor interactions independent of the JAK2-STAT5 signaling pathway responsible for IGF-1 release and anabolic effects. Certain terminal and mid-sequence hGH fragments are hypothesized to retain amphipathic helical conformations that allow preferential binding to beta-adrenergic or GH receptor subtypes on adipocytes, activating adenylyl cyclase and increasing intracellular cAMP, which in turn activates protein kinase A (PKA) and hormone-sensitive lipase (HSL) to catalyze triglyceride hydrolysis. For Frag 17-23 specifically, mechanistic receptor-binding studies are absent from the peer-reviewed literature, meaning these proposed mechanisms are extrapolated from related GH fragment research rather than directly demonstrated.
Following subcutaneous administration, the peptide enters systemic circulation and is subject to rapid proteolytic degradation given its short sequence, resulting in an estimated half-life of 1–2 hours. Distribution to adipose tissue would be governed by passive diffusion and any receptor-mediated uptake. At the adipocyte level, proposed cAMP elevation would upregulate HSL activity, increasing free fatty acid mobilization into circulation. Unlike intact hGH, the fragment lacks the binding sites required for strong GH receptor dimerization and subsequent STAT5 phosphorylation, theoretically minimizing IGF-1 elevation, insulin resistance, and tissue growth side effects.
Pharmacodynamics
Given the estimated short half-life (~1–2 hours), peak plasma concentrations would be achieved within 30–60 minutes of subcutaneous injection. Any acute lipolytic signaling would parallel this pharmacokinetic curve. Measurable changes in body composition require chronic administration over weeks, with fat oxidation effects compounding over a 4–8 week period.
Anticipated physiological changes include incremental increases in circulating free fatty acids post-injection, potential modest reductions in adipose tissue mass over multi-week cycles, and theoretically no significant alteration of fasting insulin, IGF-1, or glucose homeostasis — though none of these endpoints have been rigorously measured in human trials for this specific fragment.
Timeline
- Days 1-3: Peptide achieves steady-state kinetics with daily dosing. Transient cAMP elevation in adipocytes may occur acutely post-injection, but no clinically detectable changes in body composition at this stage. Injection-site tolerance is established.
- Weeks 1-2: Cumulative lipolytic signaling hypothetically begins to increase basal rates of free fatty acid mobilization. Users may notice slightly enhanced fat oxidation during fasted cardio or training. No significant changes in scale weight expected at this phase.
- Weeks 2-8: If the peptide demonstrates efficacy, progressive improvements in body composition — primarily fat mass reduction — would be expected in this window. Maximal effects are likely modest and dependent on concomitant caloric deficit and aerobic activity. Without controlled human data, outcome prediction remains speculative.
Comparisons
- Frag 17-23 — effectiveness Low, safety Moderate, cost $$, Medium to use
- HGH Frag 176-191 — effectiveness Moderate, safety Good, cost $$, Medium to use
- AOD-9604 — effectiveness Moderate, safety Good, cost $$$, Medium to use
- CJC-1295 + Ipamorelin — effectiveness High, safety Good, cost $$$, Medium to use
Adverse effects
Common:
- Transient injection-site erythema and induration secondary to peptide-mediated local immune activation
- Mild orthostatic hypotension theoretically possible through adrenergic modulation at higher doses
Rare:
- Immune hypersensitivity reaction (incidence unknown; class effect for peptide therapeutics estimated <1%)
- Theoretical dysregulation of lipid metabolism with prolonged supraphysiological dosing
Contraindications & risk mitigation
Contraindicated in:
- Individuals with active or history of hormone-sensitive malignancies given theoretical growth-signaling concerns
- Patients with known disorders of lipid metabolism or familial hypertriglyceridemia
- Individuals on insulin or oral hypoglycemic agents due to theoretical additive hypoglycemic risk
- Cycle with periodic breaks (4–8 weeks on, 4 weeks off) to avoid receptor desensitization and monitor for unintended metabolic effects
- Baseline and follow-up lipid panels, fasting glucose, and IGF-1 levels recommended to monitor for metabolic perturbation
- Use bacteriostatic water for reconstitution and maintain cold-chain storage to preserve peptide integrity and minimize endotoxin risk
Qué hace
Some users anecdotally report reduced body fat, particularly in stubborn areas, and a slight improvement in definition. These changes are subtle and depend heavily on diet and training.
Cómo funciona
Imagine growth hormone is a master key that opens many different doors in your body. Frag 17-23 is like a small copy of just one tooth on that key — it might still open the 'fat-burning door' without unlocking all the other doors that could cause side effects.
When administered under the skin, Frag 17-23 is thought to travel through the bloodstream to fat cells, where it may signal them to break down stored fat and release it as energy. Unlike full growth hormone, it theoretically does not strongly stimulate muscle growth or insulin-related pathways.
Qué esperar
Effects, if any, are typically not noticeable in the first week. Most users report subtle changes in body composition after 3–6 weeks of consistent use alongside diet and exercise.
- Week 1: Peptide is establishing baseline levels; no noticeable effects typically reported. Mild injection site reactions may occur as you adjust to the protocol.
- Weeks 2-4: Some users begin to notice very subtle changes in how their body responds to caloric restriction. Energy levels may feel slightly more stable, and some report minor improvements in definition.
- Weeks 4-8: Any meaningful changes in body composition would be expected in this window, primarily if accompanied by a caloric deficit and regular exercise. Results vary significantly between individuals.
Bueno saber
- Always reconstitute with bacteriostatic water and use sterile injection technique
- Start at the lower end of the dose range (250 mcg/day) and assess tolerance before increasing
Manteniéndose seguro
- Mild redness or soreness at the injection site
- Occasional mild headache
Evitar si tienes:
- People with a history of cancer
- Pregnant or breastfeeding individuals
- Anyone under 18 years of age
Mecanismo de acción
Frag 17-23 represents amino acids 17 through 23 of the 191-amino-acid human growth hormone sequence. Growth hormone exerts lipolytic effects partly through direct adipocyte receptor interactions independent of the JAK2-STAT5 signaling pathway responsible for IGF-1 release and anabolic effects. Certain terminal and mid-sequence hGH fragments are hypothesized to retain amphipathic helical conformations that allow preferential binding to beta-adrenergic or GH receptor subtypes on adipocytes, activating adenylyl cyclase and increasing intracellular cAMP, which in turn activates protein kinase A (PKA) and hormone-sensitive lipase (HSL) to catalyze triglyceride hydrolysis. For Frag 17-23 specifically, mechanistic receptor-binding studies are absent from the peer-reviewed literature, meaning these proposed mechanisms are extrapolated from related GH fragment research rather than directly demonstrated.
Following subcutaneous administration, the peptide enters systemic circulation and is subject to rapid proteolytic degradation given its short sequence, resulting in an estimated half-life of 1–2 hours. Distribution to adipose tissue would be governed by passive diffusion and any receptor-mediated uptake. At the adipocyte level, proposed cAMP elevation would upregulate HSL activity, increasing free fatty acid mobilization into circulation. Unlike intact hGH, the fragment lacks the binding sites required for strong GH receptor dimerization and subsequent STAT5 phosphorylation, theoretically minimizing IGF-1 elevation, insulin resistance, and tissue growth side effects.
Farmacodinamia
Given the estimated short half-life (~1–2 hours), peak plasma concentrations would be achieved within 30–60 minutes of subcutaneous injection. Any acute lipolytic signaling would parallel this pharmacokinetic curve. Measurable changes in body composition require chronic administration over weeks, with fat oxidation effects compounding over a 4–8 week period.
Anticipated physiological changes include incremental increases in circulating free fatty acids post-injection, potential modest reductions in adipose tissue mass over multi-week cycles, and theoretically no significant alteration of fasting insulin, IGF-1, or glucose homeostasis — though none of these endpoints have been rigorously measured in human trials for this specific fragment.
Cronología
- Days 1-3: Peptide achieves steady-state kinetics with daily dosing. Transient cAMP elevation in adipocytes may occur acutely post-injection, but no clinically detectable changes in body composition at this stage. Injection-site tolerance is established.
- Weeks 1-2: Cumulative lipolytic signaling hypothetically begins to increase basal rates of free fatty acid mobilization. Users may notice slightly enhanced fat oxidation during fasted cardio or training. No significant changes in scale weight expected at this phase.
- Weeks 2-8: If the peptide demonstrates efficacy, progressive improvements in body composition — primarily fat mass reduction — would be expected in this window. Maximal effects are likely modest and dependent on concomitant caloric deficit and aerobic activity. Without controlled human data, outcome prediction remains speculative.
Comparaciones
- Frag 17-23 — efectividad Low, seguridad Moderate, costo $$, Medium de usar
- HGH Frag 176-191 — efectividad Moderate, seguridad Good, costo $$, Medium de usar
- AOD-9604 — efectividad Moderate, seguridad Good, costo $$$, Medium de usar
- CJC-1295 + Ipamorelin — efectividad High, seguridad Good, costo $$$, Medium de usar
Efectos adversos
Comunes:
- Transient injection-site erythema and induration secondary to peptide-mediated local immune activation
- Mild orthostatic hypotension theoretically possible through adrenergic modulation at higher doses
Raros:
- Immune hypersensitivity reaction (incidence unknown; class effect for peptide therapeutics estimated <1%)
- Theoretical dysregulation of lipid metabolism with prolonged supraphysiological dosing
Contraindicaciones y mitigación de riesgos
Contraindicado en:
- Individuals with active or history of hormone-sensitive malignancies given theoretical growth-signaling concerns
- Patients with known disorders of lipid metabolism or familial hypertriglyceridemia
- Individuals on insulin or oral hypoglycemic agents due to theoretical additive hypoglycemic risk
- Cycle with periodic breaks (4–8 weeks on, 4 weeks off) to avoid receptor desensitization and monitor for unintended metabolic effects
- Baseline and follow-up lipid panels, fasting glucose, and IGF-1 levels recommended to monitor for metabolic perturbation
- Use bacteriostatic water for reconstitution and maintain cold-chain storage to preserve peptide integrity and minimize endotoxin risk
Reference data
Specifications
- Molecular formula
- Estimated C-terminal fragment of hGH residues 17-23; exact formula not widely published
- Molecular weight
- ~700–900 Da (estimated based on amino acid sequence)
- Half-life
- ~1–2 hours (estimated)
- Route
- Subcutaneous
- Cycle length
- 4–8 weeks
- Storage
- Store lyophilized powder at -20°C for long-term storage or 2–8°C for up to 4 weeks. After reconstitution with bacteriostatic water, store at 2–8°C and use within 28 days. Protect from light and freeze-thaw cycles.
- Legal status
- Research chemical; not approved for human use by the FDA or equivalent regulatory bodies. Legal to purchase for research purposes in many jurisdictions but regulated or banned for athletic use by WADA.
FAQ
Common questions
What is the structural distinction between Frag 17-23 and Frag 176-191, and why does it matter?
Frag 176-191 (AOD-9604) encompasses the C-terminal region of hGH (residues 176–191) and has been studied in animal models and phase I–II clinical trials demonstrating lipolytic activity via beta-3 adrenergic receptor interaction. Frag 17-23 covers the N-proximal mid-sequence region (residues 17–23), a structurally and functionally distinct domain with no published receptor-binding affinity data or in vivo pharmacology studies. This makes Frag 17-23 far more speculative in terms of mechanism and efficacy compared to Frag 176-191.
Could Frag 17-23 elevate IGF-1 levels?
Based on structural reasoning, Frag 17-23 lacks the full receptor-binding interface of intact hGH required for JAK2 activation and downstream STAT5-mediated IGF-1 transcription. However, without published receptor-binding or pharmacodynamic studies in humans, IGF-1 neutrality cannot be definitively guaranteed. Monitoring IGF-1 levels during use is advisable.
What is the evidence level?
This compound is classified as Anecdotal. Evidence relies primarily on self-reported user experiences. Controlled studies are lacking.
Research
Research & sources
Current evidence for Frag 17-23 is rated as Anecdotal. No controlled clinical research is available.
- 1. Lipolytic and antilipogenic properties of a growth hormone releasing peptide and its analogues in 3T3-L1 adipocytes (2005) — American Journal of Physiology - Endocrinology and Metabolism
- 2. AOD9604: An anti-obesity drug with some of the effects of growth hormone (2006) — Journal of Endocrinology and Metabolism (general GH fragment literature)
- 3. Growth hormone and adipose tissue: beyond the adipokines (2010) — Endocrine Reviews
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