What clinical trials show for peptides and anabolic-androgenic steroids (AAS), studied separately, since almost no study has compared them head-to-head.
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Introduction
Clinical evidence on the comparative efficacy and safety of peptides versus anabolic-androgenic steroids (AAS) is thin, because almost no study has tested one against the other. This page reviews the research for each class separately. For how their mechanisms differ, see why peptides and AAS aren't direct competitors.
Clinical Evidence for Peptides
Growth Hormone Secretagogues
Human studies show effective GH release stimulation. In a 2-year trial of 65 adults aged 60-81, oral MK-677 (a non-peptide drug usually grouped with these) at 25 mg daily raised GH and IGF-1 to young-adult levels
Generally well-tolerated in that trial, though fasting glucose rose and insulin sensitivity fell
Effects on body composition documented but small: fat-free mass rose 1.1 kg, with no change in strength or function
BPC-157 and Healing Peptides
Animal studies show promising healing effects; a 2025 systematic review found 35 preclinical studies but no clinical safety data
Limited human data: as of October 2026, no controlled human trial has published results (see our BPC-157 profile)
Mechanistic studies, mostly in rodents, support theoretical benefits
IGF-1 Related Peptides
Recombinant IGF-1 (mecasermin) has documented effects on growth
Used clinically for growth disorders: it's a prescription medicine for children with severe primary IGF-1 deficiency
Side effect profiles established, with hypoglycemia the main label warning. As of October 2026, we found no published human studies of IGF-1 LR3, the analog sold as a research peptide
Clinical Evidence for AAS
Efficacy Data
Strong evidence for muscle and strength gains. In a 1996 trial, 43 men given 600 mg of testosterone enanthate weekly for 10 weeks gained more muscle size and strength than men on placebo
Dose-dependent effects documented
Well-characterized pharmacology
Safety Concerns
Clear evidence of adverse effects, mostly from observational studies of users
Cardiovascular risks documented: in a 2017 study, long-term AAS users had weaker heart function and more coronary plaque than non-using weightlifters
Hepatotoxicity with oral compounds, almost all of it from 17α-alkylated steroids
Endocrine disruption well-established: in a 2017 meta-analysis, most users had hypogonadism lasting weeks to months after stopping
Direct Comparison Studies
We found no head-to-head trials, so this table summarizes the separate evidence above.
