I see the idiotic idea of going on a 100 mile ride with no food deserves some flaming, but having on a couple of occasions bonked pretty severely I find the question interesting. First time was a long time ago when I stealthcamped and just started riding the next morning without breakfast. (young and even more stupid than today). Ended up very dizzy and sick and was saved by a grocery store in the middle of nowhere that sold cookies. Second time was on a very long forestroadride where I also got quite dizzy and sick and barely made it to a cabin that sold chocolate. If no sugar or food is available I would guess that we nondiabetics would get our bloodsugar back up again just by resting for a while and let the body transform fat into sugar. It would be nice to know for sure though.