Carbohydrates provide the body with heat and can be classified into simple or complex forms. They consist of carbon, hydrogen, and oxygen and include sugars, starches, and fibers. Carbohydrates are grouped into monosaccharides, disaccharides, trisaccharides, polysaccharides, and heterosaccharides. They can also be categorized as simple starchy, complex starchy, or complex fibrous carbohydrates. Simple carbohydrates like glucose and sucrose are made of 1-2 sugar molecules while complex starches like whole grains have longer sugar chains. Complex fibrous carbohydrates are found in green vegetables and provide vitamins, minerals and fiber.