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Peptide literacy in six short lessons
Most bad decisions in this space come from not being able to read a study. A few minutes each, a check at the end of every one, progress saved on this device.
What a peptide actually is
A peptide is a short chain of amino acids — usually two to fifty — joined by peptide bonds. Longer chains are called proteins. Your body makes thousands of them as hormones and signals; insulin, oxytocin and GLP-1 are all peptides, and so are the drugs built to mimic them.
Start →Lesson 2 · 5 minAnimal studies vs human trials
Evidence comes in levels. Cell and animal studies show what might happen; human trials show what does. Most compounds that look good in rodents fail in people, which is why LYO grades only on human evidence and why "the research is clear" usually means the rodent research.
Start →Lesson 3 · 4 minHow LYO grades evidence
Every claimed effect on LYO gets a grade from A to D that measures one thing: how much human evidence exists and how consistent it is. Animal and cell studies never move a grade above D. A grade is not a recommendation and not a safety rating.
Start →Lesson 4 · 6 minWhat a purity test proves — and doesn't
A purity test tells you what fraction of the powder in a vial is the intended molecule. It does not tell you how much powder there is, whether the vial is sterile, or whether the compound does anything. "99% pure" answers one narrow question and is routinely used as if it answered all of them.
Start →Lesson 5 · 5 minRegulation, region by region
A few peptides are approved medicines available on prescription. Most are not approved anywhere, are sold as "research chemicals" not intended for people, and in the EU and UK it is a criminal offence to sell them for human use. Enforcement has targeted sellers rather than buyers — but that is a description of practice, not a promise, and it varies by country.
Start →Lesson 6 · 4 minSpotting a bad claim
Most peptide claims fail one of six checks: no citation, an animal study presented as human, a mechanism offered as evidence, a testimonial offered as data, "studies show" with nothing to open, or a dose stated as if it had been established. Run the checks and most of the internet disappears.
Start →Quick check
Pick a lesson and take the check
What a peptide actually is
Question 1 of 3Every protein in your body is a chain of amino acids folded into a shape. A peptide is the same thing, only short — the usual cut-off is about fifty amino acids, though the line is a convention rather than a law of nature. Insulin is 51 and gets called both.
The body uses peptides as messengers. GLP-1 is released by the gut after a meal and tells the pancreas and the brain what to do about it. Oxytocin, growth-hormone-releasing hormone, the endorphins — all peptides, all made in one place to carry a signal to another.
What separates a peptide from a protein?