What are peptides?
2 min read
The short version
Amino acids are the building blocks your body uses to make proteins. String a few of them together, usually between 2 and 50, and you have a peptide. Longer chains fold up into proteins.
If proteins are the machinery of the body, peptides are more like the notes passed between departments: short, specific instructions such as "release some growth hormone" or "you can stop eating now".
Why each peptide does something different
The order of the amino acids decides a peptide's shape, and the shape decides which receptor it can fit, like a key in a lock. A peptide that fits an appetite receptor won't repair a tendon, and one aimed at growth hormone won't do much for skin.
This is why claims that one peptide does "everything" deserve suspicion.
How they work, in three steps
- The peptide reaches a cell with the matching receptor.
- It binds, and the cell receives a message: release a hormone, slow digestion, change how it handles sugar, and so on.
- The body carries out the instruction using processes it already has.
Natural or lab-made?
Both. Your body makes peptides all the time, including insulin, GLP-1 and oxytocin. Lab-made peptides copy those signals or tweak them so they last longer or act more strongly. Semaglutide, for example, is a modified version of the body's own GLP-1 that lasts about a week instead of minutes.
Are peptides the same as steroids?
No. Anabolic steroids are fat-soluble hormones that enter cells and change how genes are switched on across many tissues at once. Most peptides are water-soluble, bind to receptors on the surface of cells and send one specific signal. Peptides are not harmless, but they are a different class of substance and carry different risks.
How strong is the evidence?
It varies enormously. Some peptides, such as semaglutide and tirzepatide, are approved medicines tested in trials with thousands of people. Others have only been studied in cells and animals, and their effects and safety in people are unknown. Every profile in our library carries an evidence label so you can see which is which.
Are they legal?
It depends on the peptide and the country. In Australia, most peptides are prescription-only medicines, and many are not approved at all. Products labelled "for research use only" are not approved for people to use. Check with the TGA or your doctor.
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General information, not medical advice. Always follow your product's instructions and your healthcare professional.