Today is Pandava nirjala ekadasi which means one fasts from everything including water. The food for this day is air. Nothing like fresh air to rejuvenate one's senses! Actually total fast from even water may sound intimidating especially if one is not used to fasting. But as Krishna says through practice and detachment one gets the hang of it.
Fasting can be an austerity or a positive thought depending on one's mind set. It is an austerity if we think it is unnatural. After all we have this body and eating is but a natural function and stopping such a natural function seems unnatural...is it not? So every time when ekadasi approaches we may think it is something that I have to force. However we can also think it is natural because the Bhagavad Gita says we are not this body and mind. So if we gradually practice detachment from body and mind by giving up the demands of the body and mind (eating is one such demand) ekadasi will become fun versus an austerity.
One technique to keep the mind off food is to keep occupied with work. Because ekadasi is auspicious it is advised to be occupied thinking of Krishna through some form of devotional service through out the day. Trust me...we will not feel hungry. I am reminded of the verse 9.22 from Bhagavad Gita where Krishna says "But those who always worship Me with exclusive devotion, meditating on My transcendental form — to them I carry what they lack, and I preserve what they have". So Krishna will surely fill our mind and belly with higher taste to get through the day.