I think people simplify this too much. Fast metabolizer doesn't mean it just doesn't effect you. I am an ultra-fast metabolizer on CYP1A2 based on genetic te

I think people simplify this too much. Fast metabolizer doesn't mean it just doesn't effect you. I am an ultra-fast metabolizer on CYP1A2 based on genetic tests and yet I can still easily get negative side effects from caffeine. This is not an on/off thing, most of these metabolizers are rated on scale of 4 or 5 levels IIRC. I have been told the understanding of some of these metabolizer tests is not that great. They can test for it but they don't really understand how it changes things that well. The bigger thing with these tests is they point towards people of different genetic backgrounds needing different drugs or different doses of some drugs when it comes to certain treatments and that typical drug guidelines are heavily biased towards male patients with typical Northern European genetic characteristics. If you're an ultra-fast caffeine metabolizer there are apparently some drugs that don't work correctly on you. I typically try to limit myself to only 2 caffeine drinks a day. It's possible the tests can be wrong I guess. It's also possible I still metabolize it faster than usual but I have some other thing going on that makes me get jittery or anxious from caffeine easily. I suspect what happens is I just get a rush of the effects and then they wear off faster than usual but with a larger effect.