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Growth Hormone Axis Limited evidence

HGH Fragment 176-191

Growth hormone C-terminal fragment (amino acids 176-191)

Also known as: HGH Frag 176-191, AOD-9604 (related analog), Lipolytic fragment

Written and reviewed by the Peptide.it editorial team Last reviewed June 2026 · Every claim is tier-rated and sourced

In plain language

HGH Fragment 176-191 is a short piece of the growth hormone molecule studied for its reported fat-burning effects without the broader growth-promoting actions of full GH. Most evidence comes from animal studies, and the closely related analog AOD-9604 failed to show meaningful fat loss in human trials. Human evidence is weak.

What it is explored for

HGH Fragment 176-191 is built around an appealing idea, capturing growth hormone's fat-metabolism actions while leaving its growth and blood-sugar effects aside. Animal studies point in a hopeful direction, but it is important to be honest that the human evidence is weak and its closest analog failed to show meaningful fat loss in trials. Here is where it has been explored.

  • Fat metabolism and lipolysis research
  • Body-composition support
  • Separating fat effects from growth signaling
  • Preclinical metabolic research

These are areas of active interest and reported use, not proven outcomes. This peptide carries a limited evidence rating, see the evidence summary below for how strong the science actually is.

How it works

HGH Fragment 176-191 corresponds to the tail end of the growth hormone molecule, the region associated in research with fat metabolism rather than growth signaling.

  • Reported lipolysis. In animal studies it is associated with increased fat breakdown without raising IGF-1 the way full GH does.
  • Separation from growth effects. It is intended to mimic GH's fat-metabolism actions while avoiding effects on blood sugar and tissue growth.
  • Unclear receptor pathway. The exact receptor mechanism in humans is not well defined.

These effects are observed mainly in animal and cell studies. The closely related analog AOD-9604 did not produce significant fat loss in controlled human trials.

Evidence summary

Evidence for HGH Fragment 176-191 is weak in humans. Animal studies report fat-loss effects, but the most relevant human data comes from its analog AOD-9604, which failed to show meaningful weight or fat reduction versus placebo in trials. There are no convincing controlled human trials supporting fat-loss claims for the fragment itself.

Reported safety & side effects

Short-term tolerability has been reported in animal work and in AOD-9604 human studies, where it appeared generally well-tolerated but also ineffective. Long-term safety of the fragment in people is not established.

Reported in studiesGenerally well-tolerated short-term (mainly animal and analog data)
Human efficacyAnalog AOD-9604 failed to show meaningful fat loss
Human safety dataNot established for the fragment itself

Frequently asked

Is HGH Fragment 176-191 FDA-approved?

No. HGH Fragment 176-191 is not approved by the FDA for any use. It is sold as a research chemical and is not an approved medicine.

Does it actually cause fat loss in people?

The human evidence is weak. Animal studies suggest fat-burning effects, but its closely related analog AOD-9604 did not produce meaningful fat loss compared with placebo in controlled human trials.

How is it different from regular HGH?

It is just the tail portion of the growth hormone molecule, studied specifically for fat metabolism. It is intended to avoid the growth and blood-sugar effects of full growth hormone, though its real-world effects in humans are unproven.