You want fiber because it scours the colon and exercises it too. Exercise is the only way to restore it so that you never have to take laxatives again. If you get constipated due to the fiber that's okay, there are plenty of natural remedies such as triphala.
The best enema setup is a bucket not bag, as in enema bucket setups or a colema, which allows you to lie on a board over the toilet. Don't bother with the douche part, altho most bucket setups will include a douche attachment.
If your tongue is severely coated and you have flatulence, bloating or other digestive upsets, a fast can be a good way to begin, but it's not mandatory. And you can do the P&B shakes WITH the fast for best results.
A combination of P&B shakes and enemas is IDEAL. :)
For more information, please peruse my notes, especially Bowel Management for Beginners. :)