My wife Kristine just completed Whole30, a monthlong diet/cleanse of sorts which is intended to help you recognize what foods you have a hard time digesting. Those on Whole30 drastically scale back what they can eat (essentially just to meats, vegetables, and fruits), slowly introducing other food groups back into their lives to see what their bodies disagree with. In explaining the program, the creators of Whole30 likened it to living near a tree which you have an allergic reaction to. If you lived in the area for years, you might totally forget that the allergy exists, dealing with minor (but real) problems day in and day out. Yet if you took an extended vacation away and came back to your home, you just might realize how much that tree is making you sick.