The chosen valedictorian is often the student with the highest ranking among his/her graduating class. The term is an Anglicised derivation of the Latin vale dicere (to say farewell), historically rooted in the valedictorian's traditional role as the final speaker at the graduation ceremony.
The human body cannot survive without food and water for long periods of time. In fact, according to SurvivalTopics.com, the longest a person can go without water is 10 days--without food, it's four to six weeks.
There are many reports of obese people surviving for more than 100 days without food, but there is no way to prove these people truly ate nothing at all the entire time.