Sugar is a simple carbohydrate which means it is broken down quickly by the body and used as a source of energy. Sugars include monosaccharides, disaccharides, trisaccharides and oligosaccharides. As the names suggest, multiple sugar molecules (monosacharides) can be combined.
Monosaccharides are the simplest form of carbohydrates. They consist of one sugar and include glucose, fructose, galactose, xylose and ribose.Disaccharides are made up of two monosaccharides and include sucrose (table sugar), lactose and maltose.
Like other carbohydrates, sugar contributes 4 calories per gram.