I think it really all depends on the person and how your body is functioning. I do think that some people are able to lose weight by Water Fasting and not gain it back, or at least maybe gain some back but remain at a lower weight than when you started. Generally, if the fast is going well for you, you feel good you are not constantly struggling with the overwhelming desire to eat while you are fasting, you don't feel stressed or anxious (this is a big one), then it is very likely you will be able to keep a lot of the weight off. People who are overly stressed while fasting (not just mentally but physically) are very likely to gain most of the weight back and possibly more. I say, if you are feeling good, then you can keep going for a while and see what you can accomplish but pay attention to your body and your mind and if either of them are really starting to 'complain' it is time to stop and go to healthy eating.