The Glycemic Index or GI is a tool some scientists use to measure the effects of carbohydrates on blood sugar levels. Simple carbohydrates are digested rapidly, and they can cause blood sugar levels to rise and then drop rapidly. The GI measures how quickly 50 grams of carbohydrates from a particular food--not 50 grams of the food itself--raise blood sugar levels compared to 50 grams of glucose. A food's GI is expressed as a percentage, with pure glucose at 100 percent.
The following example can lead to some confusion. Consider carrots and bagels. Carrots have a GI of 71, and bagels have a GI of 72. The logical conclusion is that eating carrots will raise your blood sugar as much as eating a bagel will. However, the GI is based on the amount of carbohydrate in a food. One 4 to 5 ounce bagel contains about 70 grams of carbohydrates. One cup of cooked carrots supplies only 13 grams. To eat 50 grams of carbohydrates from carrots, you would have to eat about one and one-half pounds of carrots. A serving of carrots has a much lower impact of blood sugar levels than a bagel does.
Similar foods may have a very different GI. An oatmeal cookie may have a much lower GI than a chocolate-chip cookie. That is because complex carbohydrates are digested more slowly than simple carbohydrates, in part because fiber can slow down the rate at which sugar is absorbed by the bloodstream.
Determining GI is a labor-intensive process. To measure a food's effect on blood sugar, an actual person must eat the food, and then blood must be drawn and analyzed. Blood sugar levels must be noted before and after the food is consumed, and because individuals respond differently to foods, these tests must be conducted on several people before a GI can be determined. At present, only a limited number of foods have been tested.
The following example can lead to some confusion. Consider carrots and bagels. Carrots have a GI of 71, and bagels have a GI of 72. The logical conclusion is that eating carrots will raise your blood sugar as much as eating a bagel will. However, the GI is based on the amount of carbohydrate in a food. One 4 to 5 ounce bagel contains about 70 grams of carbohydrates. One cup of cooked carrots supplies only 13 grams. To eat 50 grams of carbohydrates from carrots, you would have to eat about one and one-half pounds of carrots. A serving of carrots has a much lower impact of blood sugar levels than a bagel does.
Similar foods may have a very different GI. An oatmeal cookie may have a much lower GI than a chocolate-chip cookie. That is because complex carbohydrates are digested more slowly than simple carbohydrates, in part because fiber can slow down the rate at which sugar is absorbed by the bloodstream.
Determining GI is a labor-intensive process. To measure a food's effect on blood sugar, an actual person must eat the food, and then blood must be drawn and analyzed. Blood sugar levels must be noted before and after the food is consumed, and because individuals respond differently to foods, these tests must be conducted on several people before a GI can be determined. At present, only a limited number of foods have been tested.
Thank you Keppi. Always wonderful. You make it easy to understand.
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