Interminnet fasting is supposed to be healthy.
A good trick to use it is by fasting according to food quality. If you fast when there is low wuality food, you got two rewards at once. You enjoy health benefits of fasting, and you also eat overall better food.
PS. research shows that for 48 hours eating vs. not eating has not discrenible effect on mood and cognitive performance. http://tinyurl.com/y55r5qq
(ppl did not know they got no calories, were supplied with a drink which they did not knew caloric content)