I won't swear this holds true if you exercise intensely, since I haven't tried it, but the paleo lifestyle guys say they have no problem exercising on their "lean" days.
I don't have any problems having a rather intensive strenght training session after about 16 hours without food, and my performance does not seem to suffer. I didn't try anything more extreme than that (yet).
I don't have any problems having a rather intensive strenght training session after about 16 hours without food, and my performance does not seem to suffer. I didn't try anything more extreme than that (yet).