Why can people live longer without food than without water?

Answer 1

Lack of fluids immediately begins to cause shifts in electrolytes that all cells, muscles, and organs need. Just a few days without fluids can cause observable negative effects. But without food, the body can turn to its reserves. There are no reserves with fluid.

Answer 2

If you stop breathing then your heart stops pumping, if your heart stops pumping then your blood isn't circulating, if your blood isn't circulating then all the other organs in your body start to shut down.