The most thoroughly studied peptide in consumer circulation, and the one where the gap between the trial dose and the internet dose is widest.
what it is
Semaglutide is a synthetic analogue of GLP-1, a hormone your gut releases after eating. It binds the same receptor but resists the enzyme that would normally break it down within minutes, which is why a natural signal lasting seconds becomes a drug you inject once a week. The downstream effects are the ones GLP-1 already produces: slower gastric emptying, glucose-dependent insulin release, and a reduction in appetite that originates in the brain rather than the stomach.
what the evidence shows
This is the rare peptide with genuinely large randomised trials behind it. The STEP programme found mean body-weight reductions in the region of fifteen per cent over sixty-eight weeks in people without diabetes, and the SELECT trial reported a reduction in major cardiovascular events in people with existing cardiovascular disease and overweight. Those are hard endpoints in tens of thousands of participants, which is a different evidentiary universe from most of this field.
The most thoroughly studied peptide in consumer circulation, and the one where the gap between the trial dose and the internet dose is widest.
what stays uncertain
Weight returns for most people who stop, which reframes the drug as ongoing therapy rather than a course of treatment. A meaningful share of the weight lost is lean mass, and the long-term consequences of that are still being worked out. Gastrointestinal side effects are common enough that a substantial minority discontinue. And the trials studied a specific titration schedule under supervision — the compressed schedules discussed online have not been studied at all.
the practical note
Because approved supply has been tight, a large grey market has grown around compounded and research-labelled semaglutide. Those products are not the trial drug: they vary in salt form, concentration, and purity, and several state authorities have issued warnings after dosing errors involving them.