Fasting?

Since it's not "eating", protein drinks may be an acceptable compromise to participate and keep your body healthy.

I would wait a bit. I had a day once when I ate very little and fainted. My surgeon said he had seen people faint from low blood sugar. Maybe you could design your fast as a day of eating only very humble things sort of like Ghandi did or like the "Bowl of Beans" events on Martin Luther King Jr. day. GL Diane S