I've always attributed the daily enema I always take while fasting with the success and lack of hunger I've experienced, especially after the first few days. People often make fun of the enema, but I find that it provides a welcome break during the fast, and afterwards I always feel invigorated and don't have the craving for food I've had beforehand.
I've also found enemas to be extremely helpful during those first few days of a fast when on occasion I have experienced headaches. Following an enema, the headache often disappears before I finish on the toilet.