Doesn't water intoxication also have the potential to cause kidney failure? I recall reading that somewhere.
As for VSED: It's too difficult, and unrealistic.
Maybe if you're malnutritioned, but I can speak from personal experience with fasting, that it will just cause even more suffering than fasting normally does.
If you happen to be overweight or obese, you have more than enough fat storages to survive VSED for a reasonable time (5-10 days).
If you also have mental health problems, it also adds up, so you will most likely lose your mind before coming close to dying.