Carbohydrates provide the body with energy and are divided into two types: simple and complex. Simple carbohydrates like refined sugars and fruit are easily digested while complex carbohydrates like whole grains provide sustained energy. Carbohydrates are the primary source of fuel for the body and are broken down during digestion to be absorbed and used. Choosing whole grains, vegetables and fruits supplies carbohydrates for energy and health. Disorders related to carbohydrates include diabetes and hypoglycemia which occurs when blood sugar levels drop too low.