Just because nobody's seen him eat doesn't mean that he hasn't. Fasting for that long would kill him.
True; but just because nobody's having seen him eat doesn't mean that he hasn't, it doesn't mean that he has, either. Some of the monks (or whatever), if you watch the entire documentary, don't seem that surprised; and then there's that other eighty-something guy whom they interview, and whom scientific analysis was performed on, later on in the documentary, that allegedly hadn't eaten or drunk for years.
