Overview
hGH Fragment 176-191 is a growth hormone-related peptide. C-terminal fragment (amino acids 176–191) of human growth hormone.
With a half-life of ~18 minutes, hGH Fragment 176-191 requires daily administration in most observed protocols. Administered via SubQ injection, it has a bioavailability of approximately 75% via its primary route.
Half-life approximately 15–20 minutes. Structurally related to but distinct from tyrosinated analogue AOD-9604. Subcutaneous administration. One-compartment model.
Mechanism of Action
hGH Fragment 176-191's pharmacological activity involves the following key pathways:
Lipolytic Fragment
hGH Fragment 176-191 is a modified fragment of human growth hormone that retains the lipolytic (fat-metabolizing) region while lacking the growth-promoting IGF-1 signaling of full-length GH.
Dosing Protocols
The following protocols represent commonly observed dosing patterns. These are observational summaries, not recommendations.
Dose
250 mcg/day
Route
Subcutaneous
Frequency
2-3 times daily
Duration
4-12 weeks
Dose
500 mcg/day
Route
Subcutaneous
Frequency
2-3 times daily
Duration
4-12 weeks
Reconstitution Steps
HGH Fragment 176-191 is supplied as a lyophilized (freeze-dried) powder and requires reconstitution before use. Common vial sizes: 2 mg, 5 mg.
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1
Prepare Your Workspace
Gather the HGH Fragment 176-191 vial, bacteriostatic water, alcohol swabs, and an insulin syringe. Work on a clean, flat surface.
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2
Swab Vial Tops
Clean the rubber stoppers of both vials with alcohol swabs. Allow to air dry before proceeding to prevent contamination.
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3
Draw Bacteriostatic Water
For a 5 mg vial, draw 2 mL of bacteriostatic water. This produces a concentration of 2,500 mcg/mL for easy dose calculation with twice-daily protocols.
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4
Add Water to Peptide Vial
Slowly release the water down the inside wall of the vial. Avoid injecting directly onto the lyophilized cake. Let gravity draw the water down to minimize foam and agitation.
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5
Dissolve Gently
Allow the vial to sit for 1–2 minutes, then swirl gently until the solution is clear. Do not shake. HGH Fragment 176-191 typically dissolves quickly due to its small molecular size.
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6
Label and Store
Label the vial with the date and concentration. Store in the refrigerator at 2–8°C. Use within 28 days when reconstituted with bacteriostatic water.
Quick Reconstitution Math
5 mg vial + 2 mL bacteriostatic water = 2,500 mcg/mL. For a 250 mcg dose, draw 10 units (0.10 mL) on a U-100 insulin syringe. Use the Milligram reconstitution calculator for custom vial sizes.
Lyophilized powder is stable for up to 24 months at 2–8°C or longer at -20°C. After reconstitution with bacteriostatic water, refrigerate and use within 28 days. Protect from light.
Frequently Asked Questions
What is HGH Fragment 176-191 and how is it different from full-length HGH?
HGH Fragment 176-191 is a synthetic peptide consisting of amino acids 176 through 191 of the human growth hormone sequence. It was designed to isolate the fat-metabolizing region of the GH molecule while excluding the growth-promoting and glucose-altering regions. Unlike full-length HGH, it does not stimulate IGF-1 production or affect blood sugar levels, making its activity highly specific to lipid metabolism.
What is the half-life of HGH Fragment 176-191?
HGH Fragment 176-191 has a relatively short half-life of approximately 30 minutes following subcutaneous injection, with peak plasma levels reached within 15–30 minutes of administration. This short duration is why twice-daily dosing protocols are commonly observed – typically morning and pre-workout or evening – to extend the window of lipolytic activity throughout the day.
How does HGH Fragment 176-191 promote fat loss?
The fragment interacts with receptors on fat cells (adipocytes) linked to the adenylate cyclase pathway, increasing intracellular cAMP levels. This activates hormone-sensitive lipase (HSL), which accelerates the breakdown of stored triglycerides into free fatty acids. It simultaneously downregulates lipogenic enzymes like acetyl-CoA carboxylase, reducing the rate of new fat storage. These dual actions – enhanced fat breakdown and reduced fat synthesis – account for its specificity as a lipolytic agent.
Does HGH Fragment 176-191 affect blood sugar or insulin sensitivity?
One of the distinguishing characteristics of HGH Fragment 176-191 is its neutral effect on glucose metabolism. Unlike full-length growth hormone, which can increase blood sugar and reduce insulin sensitivity over time, the fragment does not appear to disrupt glucose homeostasis at standard dosages. This is because the fragment excludes the portions of the GH molecule responsible for diabetogenic activity.
Why is fasted dosing commonly recommended for HGH Fragment 176-191?
Fasted dosing is frequently observed because elevated insulin levels from food intake can blunt the lipolytic signaling cascade that HGH Fragment 176-191 activates. Administering the peptide on an empty stomach – typically first thing in the morning or 2–3 hours after the last meal – ensures insulin levels are low, allowing the cAMP-mediated fat breakdown pathway to function without interference. Many protocols recommend waiting 15–30 minutes after injection before eating.
How long does it take to see results from HGH Fragment 176-191?
Measurable changes in body composition are typically reported after 4–8 weeks of consistent twice-daily use. Fat loss effects are cumulative and gradual rather than immediate, as each dose contributes a discrete window of enhanced lipolysis. Results are most pronounced when the peptide is used alongside a caloric deficit, as the freed fatty acids still need to be oxidized through energy expenditure to produce net fat loss.