Carbohydrates are primarily used as a source of energy in the body. They are broken down into glucose, which serves as the main fuel for cells, tissues, and organs. When consumed, carbohydrates can be classified into sugars, starches, and fiber. They provide quick energy and are crucial for maintaining blood sugar levels. Additionally, carbohydrates play a role in storing energy and providing structure to cells. If not used immediately, excess carbohydrates can be converted into fat for long-term energy reserves.