3 days wasn't enough

Many friends have done the master cleanse, i thought i would give it a whirl. Don't know how anybody does this for an extended period, i just felt empty inside for 3 days before i ate a bunch of chocolate chip cookies. I felt like that was as long as i could go, even though i have seen others do 14 days and feeling fine. they told me that i didn't stick it out long enough to feel the effects, but i felt like the challenge of not eating for 3 days was enough so i stopped. i remember my tongue was incredibly weird through day 2 and 3, filmy and greenish. generally very uncomfortable.