Fragment 176-191

Raw C-terminal tail of HGH (residues 176–191). The unstable, unmodified precursor to AOD-9604. Half-life under 5 minutes, no human trial program - most „success data“ cited for it is actually AOD-9604 data, mis-attributed.

Research chemicalWADA S2 prohibitedInjectableLipolyticUnstable

Key facts

Common routesSC

Half-life< 5 minutes (plasma)

Typical range250–500 mcg/day

Résumé

Fragment 176-191 is the bare C-terminal sequence of human growth hormone (residues 176–191). Identified by Ng and colleagues at Monash in the 1990s as the region responsible for HGH's lipolytic effects - independent of the anabolic N-terminus, which drives IGF-1 release and creates insulin resistance.

It is essentially the unmodified form that preceded AOD-9604. AOD was engineered with an added N-terminal tyrosine residue specifically to fix the stability problem the raw fragment fails on: plasma half-life under 5 minutes, rapid solution-phase degradation, and a high probability that grey-market material is already inactive before use.

Not the same as AOD-9604

The Fragment-176-191 and AOD-9604 narratives are routinely conflated because the mechanism is identical. They are not the same compound. AOD-9604 has an N-terminal tyrosine extension that extends half-life and is the form used in trials (Stier 2013, Phase 2). Raw Fragment 176-191 has no human trial program - source it only if you have a specific argument why the raw sequence beats the stabilised one.

Notes sur le mécanisme

Beta-3 adrenergic lipolysis

Stimulates adipocyte lipolysis directly - the C-terminus of HGH does this in the full hormone too. Releases free fatty acids and inhibits lipogenesis. The mechanism is conceptually clean; the practical question is whether the molecule stays intact long enough to act.

No IGF-1 signal

Doesn't bind the HGH receptor in the liver. So no IGF-1 rise, no water retention, no acromegaly-like effects, no glucose drift. That's the genuine advantage over full HGH or GH secretagogues - when the peptide actually works.

Stability problem

Plasma half-life under 5 minutes. Lyophilised powder is reasonably stable; in solution it degrades fast. Shaking destroys it. Most users who „feel nothing“ are probably injecting degraded material rather than running a peptide that lacks effect.

Dosing patterns

Fat loss (fasted, split doses)

250 mcg SC morning fasted + 250 mcg SC pre-workout (also fasted). Insulin spikes block lipolysis completely - the fasted condition is not optional. Because of the sub-5-minute half-life there is no real steady state; each dose is a brief lipolysis window.

Cycle length

Typical cycles run 8–12 weeks if continued. Users seeing nothing after 4 weeks usually conclude sourcing failure rather than mechanism failure - the underlying expectation is real, but the material has to be intact for it to apply.

Stacking notes

Fragment 176-191 + AOD-9604 is redundant - both hit the same mechanism with different stability. If you want the stable form, run AOD-9604. Complementary stacks: GH-axis pair (CJC + Ipamorelin) for the recovery axis while the raw lipolysis wave is dosed separately.

Aperçu des données

Tier: Limited data. Rating D - the mechanism science is solid (Ng 2000) but there is no human trial program for the raw sequence. What gets cited as „Frag-176-191 data“ is mostly AOD-9604 data with the tyrosine residue dropped from the description.

Human data

None. The clinical trials you'll find online are AOD-9604 trials (Stier 2013 is the most-cited). Anecdotal bodybuilding logs are mixed - users who hold to the fasted-plus-cardio protocol report subtle effects; without protocol discipline, nothing.

Animal data

Ng et al. (2000): mouse and rat models confirmed the 176-191 region carries HGH's lipolytic activity. Significant fat loss in obese mice without lean-mass loss or glucose-tolerance change. Translatability to humans remains open.

Considérations de sécurité

Safety profile is clean. No IGF-1 risk, no insulin resistance, no glucose drift. The practical „risk“ vector is not harm - it's efficacy. You're paying for a peptide that has a high probability of arriving from the grey market as degraded material. Injection-site reactions are the only notable adverse-event class.

Common cautions

High probability of inactive material - the raw sequence is unstable and grey-market synthesis / shipping often isn't careful enough
Fasted condition not optional - insulin spikes block lipolysis completely
If the goal is the stable form with trial data behind it: run AOD-9604 rather than the raw sequence
WADA S2 prohibition applies - tested athletes should not run this in training or competition phase