I have fasted on several occasions prior to ritual , and I understand it's benefit. When I am meditating with that tired and hungry feeling (usually my fasts are about a day prior to a couple of days) I do feel closer to my dieties, more grounded. I could describe my experience as my astral bodies aligning much closer to my physical body.
However, I find that I do my best work when I am completely nourished, attentive, and awake ~ therefore i no longer fast unless my ritual work specifically requires that I do so or I feel that it is necessary (which is very rare).
I say if you want to be true to your local traditions, then maybe it wouldn't hurt to fast, but just be good to your body. It is your tool for everything you do in life.