Discuss PGroot's answer to: Can people with eating disorders live long lives? what about those on a water only diet?

Without food you will be living on stored fat, and eventually muscles are broken down.  You will also be deficient in vitamins. You might be losing 2 pounds a week if you weigh 100.  You could last for months if you started at 150. 

Hunger strikes have been known to last more than 7 weeks.