I've suffered from anorexia, and I can tell you Water Fasting while having an eating disorder is a VERY bad idea. Read some books about the nutritional value of foods and their cleansing properties, learn that food is important for making your body work right, keeping you ALIVE and keeping you beautiful.
I would just start juicing every morning, then eating lots of raw fruits and vegetables. Decrease your cooked food intake, and be mindful of your behaviour. Take the time while transitioning your diet to journal everyday and write about your emotions and the physical/emotional/mental changes you experience while changing your eating habits.