I would say most of the things you mentioned.. aren't meant to be eaten. Anything processed, really. Or not found in it's natural state. Lots of people feel bad when they eat bread. Whether they are on low carb or not. I have a gluten sensitivity and when I eat pizza, cake, rolls, etc., I feel SO awful, and I did for a few years before going to LC. So I wouldn't say I lacked the enzymes.

I can, however, eat potatoes, yuca, plantains, etc., without these problems. Most people, when complaining of these problems, are complaining that processed junk is what is giving them digestive problems and are right when they say they aren't meant for the human body to consume.