The evidence scale
T5 21 · T4 7 · T3 19 · T2 3 · T1 1
This scale does not measure how promising something is. It measures how much is known about it, and who it has been tested on. Something moves up only when published evidence justifies it — never because the explanation of how it works sounds convincing.
- T5
Approved medicine
Approved by the European or US medicines regulator for a named condition, after large randomised trials, with a public product information sheet anyone can read.
For example: Semaglutide, insulin, teriparatide
- T4
Still being tested in people
Currently in registered clinical trials in humans, but not approved anywhere yet. The trials may still fail — most drugs at this stage do.
For example: Retatrutide
- T3
Tested in people, but barely
Human studies exist, but they are small, short, uncontrolled, paid for by the seller, or they measure something easy to measure instead of something that matters.
For example: Several skincare peptides
- T2
Only tested on animals
The evidence is animal experiments, cells in a dish, or computer models. No meaningful controlled trial in humans has been published.
For example: MOTS-c, TB-500
- T1
No real evidence at all
Nothing published worth citing, in any species. What circulates is anecdote, sales material, or a guess extrapolated from something else.
For example: Several compounds sold as research chemicals