Earlier quoted context omitted.
Except major performance decrease. Some people cannot afford that.
Anecdotally I found my performance to - both in the gym and in the office - increase not decrease. From athletes and academics I follow on social media, they also say the same. I've read a few hypothesis as to why this may happen. In an evolutionary sense, when in a fasting state we would require more energy to go out and hunt/gather food to take us back out of that state. IIRC, metabolism increases while fasting. It…
I experimented at the start of the year and didn't experience any drop in performance - office or gym - with water fasts less than 24 hours.
Fasting between 24-72 hours, though, really affected my sleep and made me feel weaker during workouts (though it didn't really affect me mentally). Curious to see if others experienced the same.
Can't comment on longer fasts as I didn't exceed 72 hours (though I did read many reports of it actually getting easier after that point in time).
Currently doing IF (very rough 20/4) which is working pretty well.