First, fasting as a spiritual practice does not have to be food. Regard food I fast once in a great while for different reasons. I am diabetic type II, have a spiritual concept of self, and at times not hungry. I fast based on all three. I think the first two reasons are beneficial, but the last is questionable. It may be beneficial if viewed as the lack of appetite as an early sign of depression, so I guess in that case it is beneficial if aware.