Let we intoduce the dietry role of the carbohydrates to you first. The most basic form of carbohydrate is that of the simple sugars, the most important of which are glucose, fructose,and galactose.

When we eat complex carbohydrates (e.g. Starch), digestive enzymes in the mouth and intestines break down the polysaccharides into disaccharides and, ultimately, into glucose. It is glucose that is absorbed into the system and converted into energy.
Then you may think, why are we so concerned about the importance of eating starch? Why not just eat glucose?
Starch differs from simple sugars in a very important way. When we eat simple sugars ¡Xin sweets or in table sugar¡Xthese literally are "empty calories", because there's nothing else in the sugar. It doesn't carry other nutrients. But if you eat rice you're also getting protein, minerals, and vitamins.

Nowadays, many youngsters, especially girls, wanted to lose weight, they usually cut out the cereals. This is a totally wrong concept.
Starch has no more calories than protein ¡Xjust four per gram. And unlike some high-protein foods such as meat and dairy products, most starchy foods are almost fat free.

Good sources of complex carbohydrates include all vegetables, cereal, rice, bread, pasta and seeds, grains and legumes. It is best to consume a variety of high-carbohydrate foods to ensure that you get adequate amounts of the vitamins and minerals you need.