I do take magnesium salts and salt, plus apple cider vinegar. The brain works fine during longer fasts, can confirm the 'clarity' thing, but I do not feel happy when I can't eat for a few days. Of course thats not hunger, just addiction to food. As to seasonal health swings, yeah, not great.

I mean, they are cycling 72 kilometers while in a fasted state 3 days a week. I'm assuming that is roughly 2-3 hours of aerobic exercise at a very athletic pace. That would be a high level of exertion for a non-fasted person.