I've gone for 6 or 7 days. I was in a place where the food was no good. I figured it would be healthier to not eat than to eat food prepared by spiritually unfit people. I was not preparing the meals and I knew that my situation was temporary.

I practiced walking meditation, sitting meditation and cat naps.

Now I'm living where I don't eat unless I offer the food to Krishna and Krishna only accepts certain foods. When I travel I'm more liberal about diet but I still mentally have to offer the food first.

Diet is meaningless without sacrifice. Even though God can get what he wants and doesn't need anything the sacrifice of food for the purpose of giving the best to God and foregoing sense gratification for spiritual gratification is good.

In Vaishnava or Vedic practice there are fasting days and cycles where grains are not eaten. For me this is not practiced as I'm learning how to prepare food offering and deepening my basic practice. Eventually I will choose to follow these ancient practices but at the same time the most important aspect is that I sacrifice and offer my work (actions) and food.

I've read all the comments so far and it's a fascinating subject. The tongue is the first thing in the Age of Quarrel (Kali Yuga) that should be addressed. Eating, speaking and verbal expression is the root of much misalignment. Every day I chant Hare Krishna Maha Mantra 108*16 (1728 times) specifically and I do chant more anyway when my mind goes into a pattern of habit.

This chanting is essential as the mouth is consuming garbage, singing nonsense, lying, gossiping and craving. I noticed in my Theravada practice that my mind was so full of programming that I was constantly trying to silence it. Now in Bhakti (Devotional) Yoga I chant about 2 hours the Maha Mantra and when I finish there are hours of silence! I can top off my mental bliss by prayer or a little more chanting as needed.

Combining offering food, chanting and Vedic study of Swami Prabhupada's books is a real blessing and joy. I see things about God everywhere, including your post here.