I would transition to a juice fast. First dilute the juice 50/50 with distilled water. Gradually increase the strength of juice until you are drinking the whole juice. This will help you keep the calories down while your metabolism slowly returns to normal. When your weight stabilizes, start adding small amounts of raw fruits and a few raw veggies. The trick is to balance adding enough foods for strength and proper nutrition without packing on a lot of pounds. Of course some weight is always regained when solids are introduced. This is not fat, it is fecal material. Loss of water and fecal material accounts for a lot of the weight lost in the first three to seven days of fasting, especially water fasting.
Water only fasting is a powerful form of detox, and can help the body heal many health problems. However, it is not a good way to safely and permanently lose a lot of weight because of the slowdown of the metabolic rate. In fact the average person's metabolic rate is reduced 20-25% in a 7-10 day water fast. It can take months for that rate to get back to normal.