How does stored energy get in foods?

The primary way stored energy gets into foods is through photosynthesis, which is the process by which plants convert sunlight into chemical energy. During photosynthesis, plants use the energy from the sun to convert carbon dioxide and water into glucose and oxygen. Glucose is a simple sugar that plants use as a source of energy, and it is also the main component of starch and cellulose, two complex carbohydrates that plants store as energy reserves.

In addition to photosynthesis, some foods also get their stored energy from other sources. For example, animals get their energy from the plants they eat, and some foods are derived from animal products, such as meat, eggs, and dairy. These foods contain stored energy in the form of fats and proteins.