Rats that are continuously kept awake, die after two weeks and that is less time than it takes them to starve to death.
Human theory is when you finally run out of body fat, protein, and carbohydrates, your body runs out of energy and stops functioning. However, fat people would only be able to survive that long if they had enough vital water-soluble B vitamins in their system to help metabolize fat stores. So it is possible that a person could die of starvation and still be fat.
The longest recorded starvation was by the Irish hunger-striker Kieran Doherty in 1981, who died after fasting for 73 days.
With a supply of vitamins and water, people have been known to survive over a year without eating.
With vitamins but without water, survival time is sharply reduced. A human can be expected to survive for weeks without food, but a thirsty person deprived of water might only last a matter of days. Without water, the volume of blood in your body drops, and with it your blood pressure. Blood becomes thicker and stickier, making it harder to pump around the body, so your heart rate increases to compensate. Even in a cool environment, you wouldn't last for more than a week without water. Hmmm, a week without bacon might possibly kill a person, also.