A 5:2 plan includes two days a week of eating only fat or protein, not to exceed 500 calories. Permitted foods include, for example, eggs, fish, meat, poultry, or nuts. You can also have unlimited low- or no-calorie beverages. The other five days you eat healthy foods, without counting restricting calories or avoiding carbohydrates. For even better results, control carbohydrates on unrestricted days.