Compound family

Growth hormone, IGF-1 and growth factors

In one sentenceThe hormone, its downstream mediator, two fragments, and a myostatin blocker. One approved medicine, three laboratory reagents, and one properly tested failure.
Compounds5
Best gradeA Human growth hormone (somatropin)
Approved medicines1 of 5
Prohibited in sport5 of 5

What this family is

Growth hormone is a 191-amino-acid protein and an approved medicine for genuine deficiency, where it works well. Most of its effects run through IGF-1, made in the liver in response to it. The other members are what the grey market has made of that axis and its neighbours: IGF-1 LR3, a modified IGF-1 designed to evade its binding proteins and built as a cell-culture reagent; AOD-9604, a fragment of growth hormone developed as an obesity drug; PEG-MGF, a pegylated piece of the IGF-1 variant that muscle makes after loading; and follistatin 344, a protein that blocks myostatin, the signal that limits muscle growth, sold on photographs of double-muscled animals.

The evidence diverges sharply. In healthy older adults, a meta-analysis of randomised growth-hormone trials found about 2 kg of fat shifted to lean tissue with no change in total weight, alongside significantly more swelling, joint pain, carpal tunnel syndrome and gynaecomastia — the authors concluded it cannot be recommended for anti-ageing. AOD-9604 was tested in more than 900 participants and produced no significant difference in fat mass or weight; development was terminated for lack of efficacy. IGF-1 LR3 has never been given to a person in a controlled trial, nor has PEG-MGF — every human study of mechano growth factor measures what muscle makes on its own — and neither has injected follistatin — the six-patient gene-therapy study people cite for it delivered the gene into muscle, which is a different intervention.

All five are prohibited in sport; mechano growth factors are named on the list. Anti-ageing use of growth hormone is unlawful in the United States; deficiency is the only lawful indication.

Grade counts across the family: 1 × A · 0 × B · 0 × C · 4 × D. The best grade here, A, means established in humans. How LYO grades →

The compounds, graded

Every member with its best-supported outcome grade, human-trial count and regulatory status. Each opens the full evidence page.

Human growth hormone (somatropin)

A

An approved medicine for growth-hormone deficiency, and the original anti-ageing drug the evidence does not support.

Human trialsMany RCTs + meta-analysis
StatusApproved (Rx) for deficiency; anti-ageing use unlawful in the US

AOD-9604

D

A fat-loss peptide that was properly tested in humans — and failed.

Human trials900+ participants; no effect
StatusNot approved

IGF-1 LR3

D

A laboratory reagent sold as a muscle drug. No human trial has ever tested it.

Human trials0 controlled
StatusNot approved; research reagent

PEG-MGF

D

A pegylated fragment of a muscle-made IGF-1 variant, sold for repair and growth. Never injected into a human in any study.

Human trials0 — every human study measures the body's own MGF
StatusNot approved; research reagent

Follistatin 344

D

A myostatin-blocking protein sold as a muscle-building injection. The only human data is a six-patient gene-therapy trial — of a different thing.

Human trials0 for the injected protein; 1 gene-therapy trial (n=6)
StatusNot approved; research reagent

Comparisons

Questions

Does growth hormone reverse ageing?
The randomised trials in healthy older adults say no: small changes in body composition, no functional benefit, and a clear rise in side effects. The approval is for deficiency, where the picture is entirely different.
What is IGF-1 LR3?
Insulin-like growth factor 1 with an extension that stops it binding to the proteins that normally regulate it, so it stays active far longer. It was designed for laboratory cell culture. No human trial exists, and it is not the same molecule as mecasermin, the approved IGF-1.
Did AOD-9604 work?
No. It was one of the few grey-market peptides put through a proper clinical programme, and the pooled result across more than 900 participants showed no effect on fat mass or body weight.

Written and maintained by LYO Research — how pages are written and checked. Reviewed 23 September 2026. Grades count human evidence only. Not medical advice. Correct this page →