I know someone who carbed up on bananas, hadnt eaten a banana for 10 weeks, bloated to fuck and couldnt shit for 3 days after.
Bloated from Bananas? How many did he eat, they assimilate very well, at least for me they do, I used them as a carb up before, mash them in a bowl until they gel, spread them on apple cinnamon rice cakes, like a jelly. But yes, if you just start incorporating foods that you haven't eaten your entire prep, who knows how your system will react to it, which is why a trial carb up is good to incorporate through your prep, try certain foods and see how you react to them.