I can't say in terms of weight loss, but one important factor is that if you eat a low-calorie diet, you will suffer from hunger throughout your diet. Also, Water Fasting is not easy to do, supposedly. I never did it but people doing it seem to have very little energy, not enough to go to work for sure. I would advise a juice fast. It provides you with the basic energy you'll need to go through your days, you'll still lose a lot of weight, and you won't be hungry.

low cal is not fasting but not advice would be start with the 800 cal plan based on Joel Furham's Eat to live (which is mostly plant based) book doing that for atleast a week or so and then switch to water fasting. GOod Luck!

Also, from my personal experience of very low calorie eating, I cheat less when eating than water fasting. Some people have extraordinary willpower. I was 210 when started and wore size 16 snug fit, but now I am down to size 11 some things loose and some regular fit. I lost weight pretty fast. I started May 1st and if you are going to low cal than try starting with low carb high protein to get your body into ketosis so you can kill the hunger cravings. Once your stomach shrinks it will be very hard to eat like you used to and than you can switch over to extremely low calories, like I did 5 crackers a day w/ cheese and sometimes tuna and light mayo. Pickles work well in between. Than once you have lost a pretty good amount and really are not hungry much, you can switch to like one meal a day under 800 calories. Seriously, I'm still losing and I don't even feel different. I can eat a child size amount of frozen yogurt and a chicken sandwhich and stuff like that and I still keep losing. I hit the stepper so I can keep a nice shape w/my weight loss. This right here is like a DIAMOND plan! Seriously try it! Oh and I must admit I am taking Hydroxycut Hardcore for energy because eating this low can cause fatigue and that will just counteract the fat burn. Let me know if you decide to try it.