Peptides 101 & glossary
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Most peptides are short chains of amino acids. The popular ones like BPC-157 are usually given by subcutaneous injection because the gut would otherwise break them down. They’re often sold research-use-only, arriving as a powder that needs reconstitution with BAC water, and a trustworthy seller publishes a COA. Some act as a secretagogue, while approved GLP-1 drugs are a different story entirely.
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503A compounding
A US legal framework letting pharmacies make custom-formulated medicines for individual patients.
Agonist
A molecule that switches a receptor on. The opposite is an antagonist, which blocks it.
Amino acid
The building blocks of proteins. A peptide is a short chain of them linked together.
Amylin
A hormone the pancreas releases with insulin after a meal; it slows stomach emptying and signals fullness. Cagrilintide is a long-acting copy.
Angiogenesis
The growth of new blood vessels; a proposed mechanism behind some healing peptides.
BAC water
Bacteriostatic water; sterile water with a preservative, used to dissolve peptide powders.
BPC-157
A synthetic peptide based on a protein found in stomach acid, popular for healing, but evidence is animal-only.
Cardiolipin
A fat unique to the inner membrane of mitochondria, the cell's power plants. Elamipretide (SS-31) binds it to support energy production.
COA
Certificate of Analysis: a lab document showing a batch's purity and contents. Reputable suppliers publish them.
GHRH
Growth-Hormone-Releasing Hormone. A peptide that signals the pituitary to release growth hormone. Several research peptides are analogues.
GHRP
Growth-Hormone-Releasing Peptide. A class of synthetic peptides that mimic ghrelin to stimulate growth-hormone release.
GLP-1
Glucagon-like peptide-1. The hormone class behind approved weight-loss drugs like semaglutide and tirzepatide.
Glucagon
A hormone that raises blood sugar, insulin's counterpart. Some newer drugs deliberately also activate its receptor to burn more energy.
GnRH
Gonadotropin-releasing hormone: the brain signal that starts the reproductive hormone cascade. Gonadorelin is a synthetic copy; kisspeptin sits one step above it.
Growth hormone (GH)
A hormone that influences muscle, fat and tissue repair. Several peptides aim to raise it indirectly.
Half-life
How long it takes for half a dose to clear your system; it shapes how often something is taken.
IGF-1
Insulin-like Growth Factor 1, a growth signal made by the liver in response to growth hormone.
Incretin
Gut hormones (like GLP-1 and GIP) released after eating that boost insulin and curb appetite. The hormone family behind the new weight-loss drugs.
Intramuscular
Injected into muscle tissue; typically a deeper, larger volume than a subcutaneous injection.
MASH
Metabolic dysfunction-associated steatohepatitis: fatty liver disease with inflammation. A target for several investigational metabolic drugs.
Melanocortin receptor
A family of five receptors (MC1R–MC5R) controlling skin pigment, appetite, inflammation and sexual desire. PT-141 and melanotan act here.
Myostatin
A natural protein that puts the brakes on muscle growth. Blocking it (the theory behind follistatin hype) lets muscles grow larger.
Peptide
A short chain of amino acids. Larger chains become proteins; insulin is a well-known peptide.
Preclinical
Research stage where a compound has been tested in lab dishes or animals but not yet in controlled human trials.
Reconstitution
Mixing a freeze-dried peptide powder with liquid to make it usable. (How it's done safely is a clinician's job.)
Research-use-only
A label meaning a product is sold for lab research, not human use. A legal workaround that implies no quality control or human testing.
Secretagogue
A compound that prompts your body to release more of something. For example, growth-hormone secretagogues nudge natural GH release.
Subcutaneous
Injected just under the skin (the "pinch an inch" method), as opposed to into a vein or muscle.
WADA
The World Anti-Doping Agency, whose Prohibited List defines what's banned in tested sport.
YMYL
"Your Money or Your Life", Google's term for content (like health and finance) where quality and accuracy especially matter.