I have fasted for three straight days on many occasions and it was pretty easy for me. Drinking zero-calorie beverages (coffee, tea, water) should be fine. This is not professional medical advice and definitely do not do this if you are an alcoholic, diabetic, or pregnant. Once you break the fast, do so with moderation.
I need to survive for 3 days without pooping, and eating as little as possible. I can pee, but not very often. It can't take up too much space. What food do I pack?
Please don't ask why I need this....