Eat a diet with hardly any fibre before you go. The last time I was bunged up for 4 days I had eaten a lot of meat and not enough veggies in comparison. It'll either help, or you'll just have a very big poop idk.
I would recommend lessening your fibre as a minimum if you must though!
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....