I've got Crohn's Disease. Luckily, I am not prone to wasting away, but I seem to get partial bowel obstructions once every 12-16 months. It is hard to tie it directly to specific foods, stress, etc., but I do have trouble digesting some things. Too much fiber tears me up inside. I can eat 1 small salad per day, but more than that and I am hurting. I can tolerate nuts in very small doses.
So, on occassion I will eat 5-6 whole raw cashews, but much more than that and it is not much fun. I have found I am ok eating 2 whole grain waffles from Kashi per day, but oatmeal tears the living daylights out of me. I haven't eaten corn on the cob since 1987. There are plenty of other good foods I can tolerate and actually like, so I am not complaining (too much, anyway).