Even if you can't handle fasting (you won't have to for this idea) and can't handle much fruit, try the morning beverage Dr S has in his 5 day liver gallbladder cleanse, on any ordinary day without fasting or anything fancy going on that day. It REALLY made my stomach feel good, much different than plain fresh fruit juice would have, and none of the usual rebound from too much fruit Sugar for me (I'm one of those sentive to too much fruit).
Here is the link to the program, and the drink I'm referring to is the one with fresh apple/grape juice, garlic, ginger root, olive oil, and distilled water.
I don't have a juicer, but made it in my blender and strained off some of the pulp. I also added a dash of cayenne just because it sounded good.