HGH Fragment 176-191 for Fat Loss

Introduction

HGH Fragment 176-191 is the last 16 amino acids of growth hormone, sold for fat loss without the other effects of full GH. Vendors often call it AOD-9604, but they aren't identical. Only AOD-9604 was tested in people, and it failed on weight.

What is Fragment 176-191?

Origin and Structure

Amino acids 176-191 of growth hormone
Often called the "fat-burning" region of GH
AOD-9604 is a modified version: hGH 177-191 with an added tyrosine at the start, per FDA's 2024 review
As of October 2026, WADA's 2026 Prohibited List names both under S2.2.3, banned at all times (see peptide rules in sport)

Key Distinction

In obese mice, AOD-9604 cut weight gain without raising blood glucose. Claims of no muscle or organ growth rest on cell tests showing it doesn't bind the GH receptor, not on human data.

Mechanism of Action

Fat Cell Effects

Stimulates lipolysis in adipocytes (rodent studies)
Inhibits lipogenesis (fat storage) in rodents
Does not bind to GH receptor; FDA says the real target is unknown

Metabolic Profile

No glucose rise or insulin resistance in mice and rats
No significant IGF-1 change in the sponsor's oral and IV trials, per its authors (FDA saw no lab values)
Not measured with the injected form

Comparison to Other Options

Factor	Fragment 176-191	Full GH	GH Secretagogues
Fat Loss	Rodents only; failed in human trials (AOD-9604)	Direct	Indirect
Muscle Growth	Not studied	Yes	Not shown in trials
Blood Glucose	No rise in rodents	Increases	May increase
IGF-1 Increase	None reported (oral/IV trials)	Yes	Yes
Organ Growth	Not studied	Possible	Unclear
Cost	Moderate	High	Low-Moderate

Dosing Protocols

FDA's 2024 review found no human data on injected use; these are user reports.

Commonly Reported Use

Dose: most often 300 mcg/day; 250-500 mcg/day is typical
Frequency: usually once daily, sometimes split in two
Timing: morning fasted subcutaneous injection, an untested habit
Duration: about 12 weeks (our AOD-9604 entry lists 12-16)

Older guides' 500 mcg twice daily has no source we could find.

Trial Doses (AOD-9604)

In the OPTIONS trial, 536 adults with obesity enrolled and 502 were randomized to oral AOD-9604 (0.25-1 mg daily) or placebo for 24 weeks alongside diet and exercise.

Expected Results

What the Trials Found

OPTIONS missed its 12-week weight-loss endpoint, and the sponsor stopped development for obesity in 2007. FDA's 2024 review found AOD-9604 failed to beat placebo on weight in most studies.

Realistic Expectations

User reports are mixed: many notice nothing after 12 weeks, while a minority report losing inches. Untested gray-market vials may explain part of that.

Optimal Use Conditions

Users nearly always pair it with a calorie deficit and resistance training, so any loss is hard to credit to the peptide.

Stacking Options

With GH Secretagogues

Some users add Mod GRF 1-29 and ipamorelin to raise GH too. That's untested and reintroduces the IGF-1 and glucose effects the fragment is chosen to avoid. See our CJC-1295 fat-loss article and ipamorelin fat-loss article.

Sample Combined Stack

A forum schedule (reported, not tested):

Peptide	Dose	Timing
Fragment 176-191	250mcg	Morning fasted
Ipamorelin	100mcg	Post-workout
Mod GRF 1-29	100mcg	Post-workout
Fragment 176-191	250mcg	Pre-bed fasted
Ipamorelin	100mcg	Pre-bed

Side Effects

Reported in Trials and by Users

Injection site irritation (users)
Occasional headache and diarrhea (oral and IV trials)
Chest tightness and euphoria, possibly related (IV trial)
Cancers in one 12-week oral trial (investigators judged them unrelated; FDA was unsure)

What the Safety Data Cover

FDA's December 2024 review called the human safety data limited and insufficient to support long-term use. It proposed not letting US pharmacies compound AOD-9604.

What We Still Don't Know

Nobody knows what injected Fragment 176-191 or AOD-9604 does to body fat in people, or how safe months of use are.