The humps on a camel's back are actually huge heaps of fat and flesh that can weigh as much as 80 pounds in a healthy camel. These humps help camels survive for weeks without food and water.
When water and food become scarce in the deserts where camels roam, the fatty humps serve as stored food and are used for nourishment. As the camel's body metabolizes or uses up the humps' stored fat, the hump becomes smaller and flabbier. So the longer the camel goes without eating, the smaller its hump gets. The size of a camel's hump helps determine a camel's health, food sources, and overall well-being.
These humps, or reserves of fat, are the reason why camels can go for days without water and food. While humans are supposed to drink 8 glasses of water a day, camels can go without water for nearly 2 weeks!