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The glycemic index or glycaemic index (GI) is a number associated with a particular type of food that indicates the food's effect on a person's blood glucose (also called blood sugar) level. A value of 100 represents the standard, an equivalent amount of pure glucose.〔(【引用サイトリンク】title=Glycemic Index Defined )〕 The GI represents the total rise in a person's blood sugar level following consumption of the food; it may or may not represent the rapidity of the rise in blood sugar. The steepness of the rise can be influenced by a number of other factors, such as the quantity of fat eaten with the food. The GI is useful for understanding how the body breaks down carbohydrates〔(【引用サイトリンク】title=Glycemic Index Food List & Chart )〕 and only takes into account the available carbohydrate (total carbohydrate minus fiber) in a food. Although the food may contain fats and other components that contribute to the total rise in blood sugar, these effects are not reflected in the GI. The glycemic index is usually applied in the context of the quantity of the food and the amount of carbohydrate in the food that is actually consumed. A related measure, the glycemic load (GL), factors this in by multiplying the glycemic index of the food in question by the carbohydrate content of the actual serving. Watermelon has a high glycemic index, but a low glycemic load for the quantity typically consumed. Fructose, by contrast, has a low glycemic index, but can have a high glycemic load if a large quantity is consumed. GI tables are available that list many types of foods and their GIs. Some tables also include the serving size and the glycemic load of the food per serving.〔 A practical limitation of the glycemic index is that it does not measure insulin production due to rises in blood sugar. As a result, two foods could have the same glycemic index, but produce different amounts of insulin. Likewise, two foods could have the same glycemic load, but cause different insulin responses. Furthermore, both the glycemic index and glycemic load measurements are defined by the carbohydrate content of food. For example, when eating steak, which has no carbohydrate content but provides a high protein intake, up to 50% of that protein can be converted to glucose when there is little to no carbohydrate consumed with it. But because it contains no carbohydrate itself, steak cannot have a glycemic index. For some food comparisons, the "insulin index" may be more useful. ==Accuracy== Glycemic index charts often give only one value per food, but variations are possible due to variety, ripeness (riper fruits contain more sugars increasing GI), cooking methods (the more cooked, or over cooked, a food the more its cellular structure is broken with a tendency for it to digest quickly and raise GI more), processing (''e.g.'', flour has a higher GI than the whole grain from which it is ground as grinding breaks the grain's protective layers) and the length of storage. Potatoes are a notable example, ranging from moderate to very high GI even within the same variety.〔 The glycemic response is different from one person to another, and also in the same person from day to day, depending on blood glucose levels, insulin resistance, and other factors. Most of the values on the glycemic index do not show the impact on glucose levels after two hours. Some people with diabetes may have elevated levels after four hours.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「glycemic index」の詳細全文を読む スポンサード リンク
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