With such drastic diet - gastric system goes for a toss. You don't want to wait that long between pooping. One option is to try buffered vitamin c. It was definitely give you a poop whenever you want without side effect and dependency.

I recommend the following vitamin c powder. If you are up for it you can do also a vitamin c cleanse: https://www.perque.com/product/perque-potent-c-guard-powder/