This lion does. Also a scotish person who's name I can't remember did it...only he did it for 384 days straight
The doctor told him too lose weight or die, doctor didn't tell him how, so he used simply logic "what I eat makes me fat, I stop eating I lose weight" and he did 50% of his bodyweight, some of it off course were muscle and some fat. He did occaisonally take vitamin pills but other than that he just drank water. The funny thing is that after the 384 days several doctors did check up's of every thing, because they though it was impossible to survive for more than two weeks without food, turned out everything was fine.
Yep I'm always careful....except when I'm not Besides I only do it for 48 hours at the time. It's funny though after about 24 hours you don't really feel hungry anymore.