As a Catholic, I have many days in which I need to fast. I personally enjoy those days as it helps me feel closer to my religion and God. I think it's Ghandi that fasts for long periods at a time, he says he gains clarity of thought
It is cleansing but if it causes you emotional distress, maybe you should seek counseling to deal with your emotions. It's possible that something in your subconscious needs to be dealt with and fasting is only bringing it to the surface. Heal your mind, then the body will follow. I'm no doctor but if fasting is stressful, then any benefit you get from fasting is probably negated.