HGH Fragment 176-191
Human Growth Hormone Fragment 176-191 · HGH Frag · Frag 176-191 · hGH 176-191 · Lipolytic fragment of hGH
The C-terminal tail of growth hormone, sold for fat loss on almost entirely rodent evidence.
Typical dose
250 mcg
Once daily, fasted (many split it into two 250 mcg doses)
Range
125–500
mcg
Half-life
—
see Dosing
Evidence
Animal only
Subcutaneous
What it is
HGH Fragment 176-191 is the last sixteen amino acids of the 191-residue growth hormone molecule. The premise is clean: isolate the part of GH responsible for fat mobilisation and leave behind the part that drives IGF-1, tissue growth and insulin resistance. The premise has held up better than the results.
Almost everything sold and discussed as "frag" is described using data from AOD-9604, which is not the same molecule. AOD-9604 has a tyrosine where the natural fragment has a phenylalanine, and it is the version that was actually taken through animal and human studies. The unmodified 176-191 fragment has never been tested in humans at all.
AOD-9604's own record is not encouraging. It reduced fat gain in obese rodents, then failed to separate from placebo on weight loss in a 24-week Phase 2b obesity trial, after which the obesity programme was wound down. Users who report anything from frag usually describe a mild effect on appetite and free fatty acids on top of an existing deficit, not fat loss in its own right.
How it works
In rodent work the fragment increases lipolysis and fat oxidation in adipose tissue and raises expression of the beta-3 adrenergic receptor, the main lipolytic receptor on fat cells. It does this without binding the growth hormone receptor, so it does not raise IGF-1 and does not affect blood glucose the way full-length GH does.
That separation is both the appeal and the limitation. No IGF-1 rise means no anabolic or connective-tissue benefit, and a lipolytic signal on its own changes nothing unless you are already in an energy deficit: fatty acids released but not oxidised are simply re-esterified back into fat.
Dosing
No dose has ever been validated in humans. The 250-500 mcg range is community convention scaled from rodent studies rather than a clinical figure.
Reconstitution calculator
Pre-loaded with HGH Fragment 176-191’s vial size, water volume and typical dose. Change anything.
Typical: 250 mcg · range 125–500
Draw to
10 u
0.1 mL · 250 mcg
Concentration
2.5 mg/mL
25 mcg per unit
Doses per vial
20
Vial lasts
2 weeks 6 days
Draw to 10 units on the barrel.
Once mixed
2-8 degrees C and used within about 3-4 weeks. Do not freeze once reconstituted.
5 mg in 2 mL of bacteriostatic water gives 2500 mcg per mL, so a 250 mcg dose is 10 units on a U100 insulin syringe. Run the water slowly down the vial wall and swirl rather than shake.
Storage
Before mixing
2-8 degrees C for up to about two years, kept dark and dry. It tolerates a few weeks at room temperature in transit without meaningful loss.
After mixing
2-8 degrees C and used within about 3-4 weeks. Do not freeze once reconstituted.
Reported benefits
- ▪Targets fat mobilisation without raising IGF-1 or blood glucose
- ▪No growth hormone receptor activity, so no water retention, carpal tunnel or organ growth
- ▪Does not suppress the natural GH axis, so it can be run continuously
- ▪Cheap and generally well tolerated; injection-site reactions are the main complaint
- ▪Reasonable adjunct in a calorie deficit for people who cannot use stimulants
Side effects
- ▪Injection-site redness, itching and small lumps, by far the most common complaint
- ▪Mild headache or lightheadedness in the first week
- ▪Occasional flushing or a warm feeling shortly after injecting
- ▪Very often nothing at all; a large share of users report no perceptible effect
- ▪Product identity is a real problem, since much of what is sold as 176-191 is the AOD-9604 variant or is underdosed
Do not use if
- ▪Pregnancy and breastfeeding
- ▪Known hypersensitivity to the peptide or to the benzyl alcohol in bacteriostatic water
- ▪Active malignancy, on precautionary grounds, although the fragment does not raise IGF-1
Evidence level — Animal only
Preclinical animal data — no meaningful human trials.
Not approved for human use in any country; sold as a research chemical and prohibited in sport by WADA as a growth hormone fragment.
Commonly run with
CJC-1295 no-DAC
Short-acting GHRH fragment that sharpens one GH pulse, almost always run with a GHRP.
100 mcg · 1-3x daily
Ipamorelin
The selective GHRP: a clean GH pulse with almost no cortisol, prolactin or hunger.
300 mcg · 1-3x daily
Semaglutide
Long-acting GLP-1 agonist dosed weekly; the reference compound for appetite-driven fat loss.
1 mg · Once weekly
HGH Fragment 176-191 FAQ
Is HGH Fragment 176-191 the same thing as AOD-9604?+
No, although vendors treat them as interchangeable. AOD-9604 carries a tyrosine at the first position where the natural fragment has a phenylalanine, a difference of a single oxygen atom. It matters because every study people cite for "frag" was run on AOD-9604; the unmodified 176-191 fragment has no human data whatsoever.
Does it actually burn fat?+
In obese rodents, measurably yes. In humans, the closest analogue failed to beat placebo over 24 weeks in a Phase 2b obesity trial. Treat it as a marginal adjunct to a deficit rather than a fat-loss agent on its own.
Will it affect my blood sugar or shut down my own GH?+
No on both counts. The fragment does not bind the growth hormone receptor, so it does not raise IGF-1, does not worsen insulin sensitivity and does not trigger negative feedback at the pituitary. That is its one genuine advantage over injectable GH.
Why does everyone say to take it fasted?+
Insulin suppresses lipolysis. Injecting a lipolytic agent while insulin is elevated from a meal works against the mechanism. Morning fasted or pre-bed on an empty stomach are the standard slots, ideally with 30 minutes or more before eating.
How do I know I received real product?+
Without third-party mass spectrometry, you largely cannot. Given how thin the underlying evidence is and how common substitution and underdosing are in this specific compound, it is one to spend little money on and expect little from.
References
- 1.Metabolic studies of a synthetic lipolytic domain (AOD9604) of human growth hormone — Hormone Research (2000) PMID 11146367
- 2.The effects of human GH and its lipolytic fragment (AOD9604) on lipid metabolism following chronic treatment in obese mice and beta(3)-AR knock-out mice — Endocrinology (2001) PMID 11713213
- 3.Human Growth Hormone Fragment 176-191 Peptide Enhances the Toxicity of Doxorubicin-Loaded Chitosan Nanoparticles Against MCF-7 Breast Cancer Cells — Drug Design, Development and Therapy (2022) PMID 35783198
More fat loss & metabolic
5-Amino-1MQ
Oral NNMT inhibitor aimed at fat-cell metabolism and NAD+ salvage. Mouse data only.
100 mg · once daily
AOD-9604
Modified hGH tail fragment sold for lipolysis without the IGF-1 rise of growth hormone.
300 mcg · once daily
Cagrilintide
Long-acting amylin analogue run weekly for satiety, usually alongside a GLP-1.
2.4 mg · once weekly
Liraglutide
Daily first-generation GLP-1 agonist; weaker and more injection-heavy than the weekly analogues.
1.8 mg · Once daily