Since I’ve only seen the video & gone on-line for help, I can’t say what the book says is a portion size, but counting calories, most packages say what a portion size is, or there are some guidelines available from many sources, including on-line ones. A cup of soup from dried soup mix is what Michael ate during his fasting days, so that was his portion, though I think he went to the minimum end of things to stay way below the caloric limit of 1/4 of daily calories, for the purposes of testing out the diet. I turned to spinach and onions cooked, as it was tasty, more filling and yet low calorie.