Carbohydrates are naturally occurring sugars, starches and fiber in food. All carbohydrates are made up of sugar molecules. Sugar molecules linked together form starches and fiber. Technically, a carbohydrate is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water). However, not all carbohydrates conform to this precise stoichiometric definition (e.g., uronic acids, deoxy-sugars such as fucose), nor are all chemicals that do conform to this definition automatically classified as carbohydrates (e.g. formaldehyde). [see: Wikipedia]