Thanks Archus for your reply. 4 hours sounds like a good recommendation. I generally get "hungry" before that and eat a little snack, but I can think about ignoring this hunger, or eating something compatible with what I last ate.
Yes, this is an interesting topic. I found curezone useful for information on fasting but on nutrition the quality and quantity of knowledge seems to be not as good, from the comparatively little I have researched here.