Many cultures and religions practiced periodic fasting.  I'm not sure of the best guidelines to follow for non-medically motivated intermittent fasting.  But I can certainly recommend the book on the topic, for all religions, cultures, and motivations.  I think it'd be interesting for you to read The Art of Fasting by Eugene Abbey.  I understand from my reading that the health benefits of fasting come from fasting combined with other life changes, not the simple fact of fasting.  Would you like me to order the book for you?
assistant
It depends on what you mean by "intermittent fasting" (IF).  If you’re talking about the 5:2 diet, then what you really need to know is that there’s no good scientific evidence that it helps with weight loss.
assistant
I am thinking about starting intermittent fasting.  What do I need to know?
user