HGH Fragment 176-191 monograph

HGH Fragment 176-191

Overview

HGH Fragment 176-191 is a synthetic peptide derived from the C-terminal region of human growth hormone and is marketed/used in bodybuilding circles as a fat-loss aid. The actual human evidence base is thin: it has been studied far less than prescription anti-obesity drugs, and there is no FDA-approved clinical use for body composition or performance enhancement. Where data exist, they suggest a lipolytic/anti-lipogenic signal, but real-world efficacy and dosing are not well established in humans.

Pharmacokinetics & Mechanism

• Class: Synthetic growth hormone fragment peptide; modified lipolytic peptide derived from the C-terminal region of human growth hormone
• Mechanism of action: This fragment is designed to mimic the alleged fat-reducing activity of the terminal amino acids of growth hormone while avoiding classical growth-hormone effects. Preclinical work suggests it can promote lipolysis and reduce lipogenesis in adipose tissue, but the precise human mechanism is not well established. It does not function as full-length GH and should not be assumed to reproduce GH’s anabolic, IGF-1, or tissue-growth effects.
• Target(s): Not well established in humans. Proposed activity is GH-fragment-mediated lipolytic signaling in adipose tissue; it is not a validated agonist of the full growth hormone receptor pathway in the way somatropin is. Downstream effects described in preclinical literature focus on fat metabolism rather than verified receptor binding in clinical use.
• Route(s) of administration: Primarily subcutaneous injection in bodybuilding/community use. Oral bioavailability is not established and would be expected to be poor for an unprotected peptide. No approved human route exists for this indication.
• Onset: Not well established. Community users report acute appetite/fat-oxidation effects within days to weeks, but there is no robust human onset data.
• Half-life: Not well established. Community and vendor materials often describe a very short half-life, commonly cited around 30 minutes, but this is not well validated in high-quality human pharmacokinetic studies. If any extended/depot variants are discussed online, they are not the standard HGH Fragment 176-191 molecule and should not be conflated with the base peptide.
• Metabolism / clearance: Not well established. As a peptide, it would be expected to undergo proteolytic degradation and amino-acid clearance rather than hepatic CYP metabolism. Specific human clearance data are lacking.