I'm sort of new at this too, so I'm not sure if this is good advice. I would say use fruits, because they're tasty and healthy. When I did a 7-day fast I used mostly apples, grapefruit (good for burning fat), oranges, pineapple, celery, and carrots. Occasionally I'd throw in strawberries, pears, grapes or peaches. I lost 10 lbs on this fast, so, like I said, I don't think fruit will do you any harm. Good luck!