Carbohydrates are the main source of energy for the body. Those carbohydrates come from the plant-based foods that you eat. You can either use carbohydrates right away for your energy needs or your body can convert them into fat to use later. There are three types of carbohydrates -- sugars, starches and fiber.
Simple sugars are little molecules made up of one or two sugar units. In nutrition, the most basic simple sugar is glucose, C6(H2O)6, and it is the type of sugar our bodies and brains use for energy every day. Glucose is called a monosaccharide, which means "single sugar." Other monosaccharides include fructose, galactose, and ribose. Fructose is found in fruits and in vegetables, galactose is found in milk and ribose is best known as a component in ribonucleic acid, which is a part of genetic transcription and is found in the cells in our bodies.
Complex carbohydrates are long chains of the single sugar units. For example, the complex carbohydrate we know as starch is made up of many glucose units.
Your body prefers to use glucose as the main source of fuel for daily activity. Your muscles need glucose to move and your organs need glucose to function, including your brain. While the body can make glucose from extra dietary protein and fats you may eat, it is suggested that half of your daily calories come from carbohydrates. Try to get your carbohydrates from healthy sources such as whole grains, fruits and vegetables. Cookies, sodas, candy and other sweets are not so healthy.