Something i have been curious about for a while and have not seen it in the literature is whether it is safe for teenagers to fast. Specifically at what age does a fast to completion generally become safe? At what age would a 3 or 7 or 10 day fast be safe? If it is not safe for a 15 year old (for example) to fast, what are the specific reasons behind it? If Water-only is unsafe for teens, what about juice only?