Our bodies are built of and powered by solely what we eat and drink. Food is the source of all of the energy needed Why do humans have to eat? Is it just because we get hungry? That is not all. People get energy from food. We need energy all the time, when we run, jump, sing, and even when we sleep. We create all the energy we need by eating. The structures components that make up the human body, such as muscles, organs, and bones, are also composed of the nutrients contained in food, meaning that it is. This is why eating and taking in the nutrients that provide energy and become the components of our bodily structures is essential to for sustaining human life.