There is an actual "diet" that morons use where they don't eat or drink anything. These idiots think they can live on air and sunlight or some something ****ing ridiculous like that. Look up "Breatharianism"
Many 'breatharians' in reality exist on very small amounts of raw food. It seems to usually be tied in with an ascetic way of life. It's the polar opposite of how most folk eat (ie. massively to excess) which also kills them.