Hi Sky! :)
It's not always about the foods so much as about the preparation of the foods and the combination in which you eat them. You must must must follow the guidelines for eating for digestive power (see FAQ) and it's a good idea to find out what Dosha you are and stick with foods/lifestyle habits that balance and pacify that Dosha (Ayurvedic Medicine's word for Body Type).
At the same time it would be good to use a fiber-based intestinal cleanser that has a LOT of herbs that are good for digestive function and gentle laxatives. Triphala is a great, safe laxative, as is fennel tea. You could still have some old meals stuck to the walls of your intestine. I'm finding that P&B shakes are often best used in conjunction with herbs, not just by their lonesome, for best effect.
Concurrently you should also do things for the lymph and to raise the metabolism of that area by applying castor oil packs at least 2 hours a night for at least 3 nights a week, if not more. Please see the post on castor oil packs in the FAQ and you'll see a link to a post by a CureZone member who had great results! :)
Hope that helps! :)