Medical experts usually say the average person can live for 4 to 6 weeks without food. The amount of time someone can go without water is much shorter, roughly a week (or less).
Your employer can force you to take leave at a particular time as long as they give you at least two weeks' notice. However, it is common for employer and employee to come to an agreement about the timing of annual leave. If you put in a request for leave, your employer has to have a good reason to refuse it.
1 For those employees who elect, with a corresponding adjustment to their prevailing rate, employees are eligible for and shall be granted noncumulative annual leave based on the rate of one hundred forty (140) hours (17 1/2 days) or one hundred eighty hours (22 1/2 days) for a full year of service each year.