Complex carbohydrates are essential for nutrition as they provide a primary source of energy for the body. These carbohydrates, found in whole grains, fruits, and vegetables, break down slowly, supplying glucose steadily, which is crucial for brain function and physical activity. Additionally, their high fiber content supports digestive health and helps maintain satiation, reducing the likelihood of overeating. In summary, complex carbohydrates are vital for sustained energy, nutrient intake, and overall well-being.