While fasting, you need to do a Colon Cleanse EVERY day to help the body offload toxins quickly. The lax tea/swf combo is great, but I have done lots of long fasting and the swf is not the most convenient thing on the planet. You can do a plain water enema anytime you need one, once or even twice a day while fasting.
When you are not fasting, you should have no need for this type of assistance. If you do, it indicates you are constipated and should correct your diet/exercise! An occasional enema (or swf) if you are blocked, is fine... but generally your diet and exercise program should move your bowels effectively, or you should know the reason why!