Why do we fast? Eating and drinking is a pervasive act that preoccupies us for much of the day so when we fast, we are reminded continuously of the reason behind the fast – like the proverbial knot in the handkerchief it nudges our memory. So when I fasted yesterday for Janmaashtami it was to remember Krsna and the example he set, and the wisdom he imparted (which the world seems to comprehensively ignore).
Beyond this, fasting is a physiological act of purification. In nature sick animals (and indeed even humans) lose appetite as our bodies look to aid the healing by giving our digestive system a break. When we do eat during a fast, it is sattvic food and drink – fruits, nuts, wholesome milk (I avoid the latter as there is pretty much no such thing easily available anymore). So even if you aren’t taking your yoga to the dinner table, it’s at least one day that you will save yourself from eating bad food or drink.
So…Jai Shri Krsna.