I fast a few times per year. It's a "smart fast", meaning that I don't deprive myself of essential nutrients even though I don't eat food. I make clear broth from vegetables, and drink that, but the main thing I ingest while fasting in an enzyme drink which the company claims is made from 50 different kinds of fermented fruits, 50 of fermented veggies, and 50 of fermented herbs. I do not feel hungry while on this fast, though I'm pretty low energy, and don't feel at my best. But I feel and look good after I finish once I've eaten a big meal. Once I had a physical post-fast, and everything was perfect.