Sugar and starch are important carbohydrates in our diet.==Sugar occurs naturally in fruits such as mangoes & pineapples. Sugar from sugar cane is extracted as sucrose (table sugar) & used in prepared foods such as biscuits & sweet drinks.===Although all foods provide us with energy; carbohydrates are the cheapest & most readily available source of energy. They contain the elements carbon;hydrogen & oxygen.When carbohydrates are oxidized to provide energy by respiration; they are broken down to carbon dioxide & water. One gram of carbohydrate can provide;on average; 16 KJ energy.==lf we eat more carbohydrates than we need for energy; the excess is converted to either glycogen or fat. The glycogen is stored in the liver & muscles; the fat; in fat depots around the kidneys & other internal organs & under the skin.