A carbohydrate is a macromolecule mostly, found in bread, pasta, beans, potatoes, cereal, and some vegetables. Carbohydrates can also provide your body with a temporary boost of energy, resulting in many marathoners compnsuming a bowl of pasta the night before. The way carbs do that is by breaking down inside the body to create glucose, the thing that gives you energy. Most carbohydrates come from foods of plant origin. The major simple carbohydrates or sugars are glucose, maltose, fructose, and sucrose which come from plants. We generally think of grains as the only source of.