how much sustenance do you think you need? anyone who has done a fast knows. in my younger years, there were some irish guys who went on a hunger strike to protest britains possession of northern ireland. it took those folks over 60 days to get near death and i believe they were water only.
the way i do it is to eat at the end of the day. i will eat in one or two or three courses, depending on what i am eating and how it should be mixed. so i might eat over the course of a few hours in the evening. i dont eat breakfast or lunch. its too draining.