Carbohydrates, one of the four macromolecules of life, can make up a large part of your diet on any given day. Carbohydrates are made up of linked sugar molecules. Carbohydrates range in size from simple carbohydrates with one or two sugar molecules, to complex carbohydrates which can have hundreds of molecules linked together, notes the Harvard School of Public Health.
The presence of carbohydrates in food gives you a very important source of energy. The energy comes from the breakdown of the carbohydrates into its constituent components. Excess carbohydrates not immediately used for energy gets stored as glycogen. When glycogen storage reaches capacity, the excess carbohydrates gets stored as fat. While the use of carbohydrates as an energy source in your body is important in its own right, the presence of carbohydrates prevents the body from using protein in the body for energy.
Carbohydrates begin as molecules of sugar. Each molecule of sugar consists of a carbon backbone, with hydrogen and oxygen molecules attached to the carbon at different positions. The varying position of these atoms is called stereoisomerism and creates different sugars while maintaining an identical molecular formula. One example, according to Encyclopaedia Britannica, comes from the sugars fructose and glucose which each have six carbon atoms, 12 hydrogen atoms and six oxygen atoms. Carbohydrates have chains of different lengths, but also have different orientation. Some chains of sugar are straight and even, while other chains branch off in many directions.
Simple vs. Complex
Simple and complex carbohydrates define two groups of carbohydrates commonly associated with foods. Simple carbohydrates are those which have smaller chains of sugars linked together, and in general provide a faster source of energy, as they metabolize faster in the body. Complex carbohydrates have longer chains of sugars and take much more time to metabolize than simple carbohydrates. Complex carbohydrates include many foods made of grains, such as pasta and breads.