Key papers ✓ 3✗ 2~ 1? 3

• ? Inconclusive reviewFront Endocrinol (Lausanne) · 2026

  The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.

  No new data

  Narrative review of unregulated GH-IGF-1 axis peptides including PEG-MGF

  Review of unregulated GH-axis peptides including hGH 176-191 (AOD9604) notes no approval for physique/performance uses, uncertain product composition, and reported adverse effects across the class such as dysglycaemia and injection-site reactions.

  Study details

  Authors' conclusion

  Peptides are stratified into evidence tiers from regulatory-grade trial data to no human studies; performance benefits are uncertain, and the authors propose a clinical assessment algorithm without legitimising off-label use.

  Limitations

  Narrative review; some peptides lack human studies.

  DOI 10.3389/fendo.2026.1822475PubMed 42395176Free full text
  Figure 2 Figure 1
• ? Inconclusive reviewJ Sports Med Phys Fitness · 2026

  A new era of doping? Use of peptide and peptide-analog drugs in recreational and professional sport and bodybuilding: a critical review.

  No new data

  Critical review of peptide use in sport and bodybuilding (includes Frag 176-191)

  Critical review: Frag 176-191 and similar peptides are promoted for fat loss, but clinical evidence for sport use is limited and unregulated products are often mislabeled or contaminated.

  Study details

  Authors' conclusion

  Clinical evidence for peptide use in sport is limited and peptides remain experimental with poorly defined long-term risks; their use should be considered high-risk and ethically problematic.

  Limitations

  Prevalence studies are lacking and most studies do not reflect bodybuilding protocols.

  DOI 10.23736/S0022-4707.26.17773-1PubMed 41880199
• ✓ Positive animalBiochem Mol Biol Int · 1994

  Reduction of cumulative body weight gain and adipose tissue mass in obese mice: response to chronic treatment with synthetic hGH 177-191 peptide.

  Animalssize not reportedLong-term

  Chronic treatment with synthetic hGH 177-191 peptide

  In obese (ob/ob) mice, long-term hGH 177-191 reduced cumulative weight gain and fat mass and inhibited fat production in adipose tissue.

  Study details

  Studied

  Obese C57BL/6J (ob/ob) mice

  Compared with

  Untreated mice (implied)

  Main outcome

  Cumulative body weight gain, adipose tissue mass, lipogenesis

  Authors' conclusion

  hGH 177-191 reduced cumulative weight gain and adipose mass and inhibited lipogenesis in obese mice; authors suggest potential for obesity treatment.

  Limitations

  Mouse study; numbers not in abstract.

  PubMed 7987248
• ~ Mixed animalBiochem Mol Biol Int · 1993

  Antilipogenic action of synthetic C-terminal sequence 177-191 of human growth hormone.

  Animalssize not reported

  Test of synthetic hGH 177-191 for antilipogenic and lipolytic activity

  In rats, the fragment blocked new fat formation like intact hGH but showed no significant fat-breakdown (lipolytic) effect.

  Study details

  Studied

  Rats (epididymal fat pads)

  Compared with

  Intact hGH

  Main outcome

  Antilipogenic activity; glycerol release

  Authors' conclusion

  hGH 177-191 had antilipogenic activity identical to intact hGH with no significant lipolytic effect, supporting that the functional domain lies in the C-terminal region.

  Limitations

  Animal tissue study.

  PubMed 8358331
• ✗ Negative animalAm J Physiol · 1978

  Hyperglycemic action of synthetic C-terminal fragments of human growth hormone.

  Animalssize not reported

  In vivo comparison of C-terminal hGH fragments (172-191 to 180-191)

  In normal rats, hGH 176-191 and related fragments caused a short rise in blood glucose, a sustained rise in insulin, and reduced insulin sensitivity.

  Key resultA single 5 nmol/kg dose of peptides containing residues 178-191 significantly reduced insulin sensitivity in insulin tolerance tests

  Study details

  Studied

  Normal rats

  Compared with

  Different fragment lengths

  Main outcome

  Blood glucose, plasma insulin, insulin sensitivity

  Authors' conclusion

  Four of the six fragments (including 176-191) caused a short-lived rise in glucose and sustained rise in insulin; shorter fragments were inert.

  Limitations

  Rat study.

  DOI 10.1152/ajpendo.1978.234.5.E521PubMed 645904
• ✗ Negative animalActa Endocrinol (Copenh) · 1982

  Effect of C-terminal chain shortening on the insulin-antagonistic activity of human growth hormone 177--191.

  Animalssize not reported

  In vivo insulin-antagonist assays of shortened Cam-hGH 177-191 fragments

  In normal rats, nanomolar amounts of modified hGH 177-191 caused significant high blood sugar and insulin resistance.

  Study details

  Studied

  Normal rats

  Compared with

  Shortened fragments

  Main outcome

  Hyperglycaemia and insulin resistance

  Authors' conclusion

  An insulin-antagonistic core of hGH lies within residues 178 to 190; shorter fragments were inactive even at much higher doses.

  Limitations

  Rat study.

  DOI 10.1530/acta.0.1010010PubMed 6751009
• ? Inconclusive in vitroBiochem Mol Biol Int · 1993

  Effect of an antilipogenic fragment of human growth hormone on glucose transport in rat adipocytes.

  Cells / lab

  In vitro glucose transport assay with hGH 177-191

  In fat cells from obese rats, hGH 177-191 reduced basal and insulin-stimulated glucose uptake, more potently than intact hGH.

  Study details

  Studied

  Adipocytes isolated from genetically obese Zucker rats

  Compared with

  Intact hGH at equimolar concentration

  Main outcome

  2-deoxyglucose uptake

  Authors' conclusion

  The peptide reduced basal and insulin-stimulated glucose uptake and was more potent than intact hGH, which may contribute to its antilipogenic property.

  Limitations

  In vitro, rat cells.

  PubMed 8118430
• ✓ Positive animalInt J Obes Relat Metab Disord · 2001

  Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment.

  Humans + animals14 days

  14-day mini-pump infusion of hGH, AOD9604 or saline, plus in vitro binding assays

  In obese ob/ob mice, 14 days of hGH or the modified fragment AOD9604 (Tyr-extended hGH 177-191) reduced weight gain and increased fat oxidation, and unlike hGH, AOD9604 did not cause hyperglycaemia or bind the hGH receptor.

  Study details

  Studied

  Obese (ob/ob) and lean C57BL/6J mice; hGH-receptor-transfected BaF-BO3 cells

  Compared with

  Saline

  Main outcome

  Body weight gain, fat oxidation, glycaemia

  Authors' conclusion

  Both hGH and its C-terminal fragment reduced weight gain, increased fat oxidation and stimulated lipolysis in obese mice, yet AOD9604 does not interact with the hGH receptor.

  Limitations

  Mouse study of AOD9604, a modified fragment rather than native 176-191.

  DOI 10.1038/sj.ijo.0801740PubMed 11673763
• ✓ Positive animalAnn Clin Lab Sci · 2015

  Effect of Intra-articular Injection of AOD9604 with or without Hyaluronic Acid in Rabbit Osteoarthritis Model.

  Animals32 animalsRandomized4-7 weeks of injections, assessed at 8 weeks

  Randomized weekly intra-articular injections: saline, hyaluronic acid, AOD9604, or both

  In rabbits with collagenase-induced knee osteoarthritis (n=32), intra-articular AOD9604 (a modified hGH fragment) improved cartilage scores and lameness versus saline, and was best combined with hyaluronic acid.

  Study details

  Studied

  Rabbits with collagenase-induced knee osteoarthritis

  Compared with

  Saline

  Main outcome

  Cartilage morphology and histology, lameness

  Sample

  32 rabbits in four groups

  Authors' conclusion

  AOD9604 injections enhanced cartilage regeneration; AOD9604 with hyaluronic acid was more effective than either alone in this model.

  Limitations

  Rabbit study of AOD9604, a modified fragment, not native 176-191.

  PubMed 26275694

Reported side effects

No human safety data in the published literature found; rat studies report raised blood sugar and insulin resistance.

✓ positive · ✗ negative · ~ mixed · ? inconclusive, judged on each paper's own main outcome. Grades: A strong human evidence → D little or none. Papers and verdicts are drawn from PubMed, Europe PMC and Russian journals (CyberLeninka); not medical advice.