The funny thing is that everybody thinks that the main challenge of being breatharian is physical, while it is not. Believe me, it isn't difficult at all to convert the body to living of light. What is very difficult is to convert the mind. Food has a deep atavic bond on us, which is difficult, although very possible, to break.
(wrongly located post, the believe me was to anonymousjane, I don't doubt that 36 knows better than me)