I will echo what beautifulbeluga says; with the exception that because I do have heart, kidney and brain involvement - I do have to be maintained on meds - so I drink MISO soup which is high in protein and sustains me when I fast.
As everyone else has recommended, I too agree that talking to your doctor and spiritual advisor would be a good idea.
Hope that you're doing well.
Take Care -
"I believe that friends are quiet angels who lift us to our feet when our wings have trouble remembering how to fly." - unknown