A carbohydrate is an organic compound with the empirical formula Cm(H2O)n (where m could be different from n); that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 (as in water). Carbohydrates can be viewed as hydrates of carbon, hence their name. Structurally however, it is more accurate to view them as polyhydroxy aldehydes and ketones. Carbohydrates are an ideal source of energy for the body.