And here I am wondering if so many human societies do ritual fast as a way to regulate behaviour during famine- an all too normal part of human history. When a groups fasts under controlled religious circumstances, their culture has a better handle on dealing with how to behave when hungry, what kinds of food are best on very empty stomachs, who gets food first (children, pregnant women, the old.) I had a friend who grew up Muslim, and although he no longer considered himself religious at all, he still fasted at Ramadan. He didn't know how to explain why, but it felt right to him. He still drank water, because he had kidney stones. I tend to think he was honoring his culture, just as I put up a Christmas tree.