In our bodies we need energy so that we could do things that are possible such as; move our muscles, talk and all the other things that we do. Without energy all humans would be useless not being able to do anything. Energy is needed to extract the oxygen from the areas in our bodies and diffuse it into our bloodstream. As warm blooded we can only digest food and function if our bodies are at a certain temperature and have enough energy, and energy is required for this. We need energy to move our muscles which also only operate when they are warm. Coldblooded humans use the energy from the environment as well as from their food. Energy is the capacity to do work in our bodies. That means doing everything that a body needs to do to stay alive and to grow: pumping ions across membranes, making new proteins, making new lipids, making hormones, making new cells, neural function, contracting muscles, replacing damaged or worn-out components, absorbing nutrients, excreting wastes and pumping blood.

Supplying enough energy to support the many functions of the body at work and play is one of the chief functions of food. This energy comes from the fats, carbohydrates, and proteins in the food you eat. Without energy stored in our bodies- our bodies would not function. It is required for the molecules to move in and out of the cells, for breaking down large molecules and also foe building new ones. The role of energy in our body consists of the breakdown of large, complex molecules to the simplest form to release energy, this is called catabolism. The opposite reaction would be anabolism; this is when energy is used to build complex structures from simple