Why do people need food? (urgent!)(ENG)

Food contains chemical energy, after people eats food our body will transfer the chemical energy into other energy, for exsample: to move or think..... If we do not eat food we will be tired because we are useing up our energy. Therefore food is very important to us.

we need food because we need the chemical energy in the food. we need the energy to move, to breath.....we need enery also when we are sleeping. we need them when we are sleeping to keep our bodies warm, keep our hearts beating and breathing...if we dont eat food, we will die after all the energy inside our bodies are used up..

2007-10-07 12:53:14 補充：
we will become hungry if the energy inside our bodies are almost used up...

If people don't eat any food, they will hungry or die.

Because if people don't eat food,they will hungry