Glycemic index (GI) is a system of classifying carbohydrate-containing foods according to how fast they are digested and absorbed during the postprandial period. It is a measure of the quality of carbohydrates based on their direct effect on blood glucose levels during 2 hours after the meal. As a reference point--glucose is used, with GI equal 100. A related concept, glycemic load (GL), take into consideration also amount of carbohydrates in portion of food. GL is calculated by multiplying the GI by the amount of available carbohydrates (g) and dividing total by 100. GI's value can be affected by a number of factors, including the variety and ripeness of food or method of processing, cooking and storage. GI of particular product, as well as mixed meal is modulated by other food components like fat, protein, organic acids, dietary fiber and also antynutrients. In general, low GI foods include most fruits and vegetables, beans and legumes, and whole grain products. Refined grain products and potatoes have a high GI. The GI has proven to be a more useful nutritional tool than is the traditional classification of carbohydrates (as simple or complex, as sugars or starches, or as available or unavailable), permitting new insights into the relation between the physiologic effects of carbohydrate-rich foods and health. Several prospective observational studies have shown that the chronic consumption of a diet with a high glycemic load is independently associated with an increased risk of obesity, developing type 2 diabetes, cardiovascular disease, and certain cancers.