Survival skills
A human being can survive an average of three to five days without the intake of water. The issues presented by the need for water dictate that unnecessary water loss by perspiration be avoided in survival situations. The need for water increases with exercise.
Hunger (2009 film)
When a note attached to a scalpel informs them that the average person can survive for, at most, 30 days without food, they realize to their horror what their captor wants them to do. As days go by and endeavours to escape prove futile, the inviolable becomes a distinct prospect. All the while, a scientist with a history observes from his study.