Why or why not?
Not in the days leading up to it (because I’m famished and that would be torture. Also, my body needs nurishment before the period starts.) And I don’t during the first two days because I lose so much blood, need sleep, and am in pain. My body is working hard - you don’t want to fast when your body needs to get something done.
I’ve done it before, and the body seems to struggle, not having the nutrients and fluids needed to complete the period. Once the heavy days are over, then I can fast and not cause any disruption, and it isn’t difficult on me. This may not be an issue for people with lighter or shorter periods.