Sounds like an allergy exclusion diet I once went on for 8 miserable weeks. Not fun. The Solanaceae (nightshade) family also includes tomatoes, but not sweet potatoes (they're in the Convolvulaceae family). I'm guessing you're going to be living on fruit, limited veg, and rice :) I think I still have recipes from my allergy exclusion days if you get stuck for interesting things to eat. I recently discovered a very tasty sweet potato, carrot, apple, and red lentil soup. Since you're doing this voluntarily, my advice would be to stop when you start getting cranky. If you hit a point where you desperately want a cup of tea, just have a cup of tea and enjoy it. No amount of "detox" is worth feeling miserable or homicidal.