I understand that eating more then you need tax your physical body as well as your mental capacity.   Fasting on food or any other things is life long exercises at least for me since when I stop fasting I don't seem to get the benefit either.  It isn't only for any special time like during Easter. 
It is like I get a break time to be free from my own attachments.  It is for me! 
I do not know if my fasting help my prayer, since I have not fasted for prayer especially.