What it means
A peptide is a chain of amino acids shorter than a protein — conventionally under about 50 residues. Most hormones are peptides: insulin (51 amino acids, at the boundary), GLP-1 (30), growth hormone-releasing hormone (44), oxytocin (9). Because they are digested in the gut, nearly all are injected, and because they are signals rather than fuels, small amounts have large effects.
Peptide drugs include insulin, semaglutide, tirzepatide, teriparatide (bone), and tesamorelin (HIV fat). "Research peptides" — BPC-157, TB-500, CJC-1295, ipamorelin, GHK-Cu and others — are compounds studied in animals or small human studies that are not licensed as medicines.
Why it matters for longevity
The licensed peptides are some of the most effective drugs in medicine, and the research ones are the most talked-about compounds in longevity. The gap between the two is evidence, not chemistry. A longevity plan that names a research peptide should say what it has been studied for, in what species, and what it has not been shown to do — and should put labs and the physician before any of it.
What the evidence says
Evidence runs the full range. Semaglutide: 17,000-person outcome trial. Tesamorelin: licensed on randomised trials showing reduced visceral fat in HIV lipodystrophy. Growth-hormone secretagogues such as ipamorelin: human pharmacology studies showing GH release, no outcome trials. BPC-157: extensive rodent healing data, a handful of small human reports, no controlled trial. Epithalon: Russian studies of uncertain quality.
The regulatory reality is that research peptides are not approved for human use, quality varies between sources, and the long-term safety of most is unknown. Those facts belong in any honest description of them.
How to measure or use it
- Read the evidence grade before the mechanism: human randomised trial, human pilot, animal, or cell culture.
- For anything that touches the GH axis, IGF-1 is the marker that shows whether it is doing anything — and the one that sets the upper limit.
- Baseline labs before, mid-cycle labs during, and a physician who knows what is being used: the three non-negotiables.
Related
- Research library — one page per compound: what it is studied for, the labs, the mistakes
- How pen clicks work — the arithmetic, if a protocol uses pens
- Baseline labs — the gate before anything
Frequently asked questions
Are peptides legal?
Licensed peptide drugs are prescription medicines. Research peptides are sold for laboratory use and are not approved for human use in most countries; rules differ by jurisdiction.
Why are peptides injected?
Because the gut digests them. Oral forms exist for a few (oral semaglutide, some BPC-157 products) with low and variable absorption.
Which peptides have real human evidence?
The licensed ones: insulin, the GLP-1 and GIP agonists, tesamorelin, teriparatide. Most research peptides have animal data and small human studies only.
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