Carbohydrates, along with fats and proteins, are one of the three types of macronutrients that provide the body with its metabolic energy. All carbohydrates are made up of smaller molecules of sugar, either singly or in long chains. Foods that are made entirely or almost entirely out of carbohydrates are table sugar, wheat flour, rice, potatoes and pasta.
Unlike fat and protein, carbohydrates cannot be stored in the body and must be absorbed into the body's cells or be kept in solution in the bloodstream. Some carbohydrates can be expelled in urine, but most are used to supply the body with energy, and the excess are generally converted to fat for storage.
Individuals with diabetes mellitus must watch their intake of carbohydrates and monitor their blood sugar and insulin levels. Individuals with hypoglycemia absorb sugar into cells quickly and cannot store them in the blood, requiring them to eat at frequent intervals to re-establish their blood sugar.