Do note that almost everyone else only abstains from food, but does drink a lot of water (often with electrolytes). It makes a huge difference, irritability and otherwise.
That's good to know. Fasting for me is partly an exercise in choosing to do something that's uncomfortable for my body to achieve a higher purpose. It is explicitly not supposed to be damaging or unhealthy in any way (people who are sick etc are discouraged from fasting). I will look into staying hydrated while abstaining from food.