The body uses glucose, a sugar, as an energy source. When someone consumes a food that contains carbohydrates, the amount of glucose in the blood increases. The glycemic index, or GI, ranks foods according to how they affect the amount of glucose in the blood. Foods that do not cause rapid increases in blood glucose are considered to have low glycemic index rankings, whereas foods that raise blood glucose levels quickly have high glycemic index rankings.
Baked Goods
The University of Sydney defines a high-GI food as a food with a glycemic index of 70 or above. Baked goods, which often employ large quantities of white flour and sugar, qualify as high-GI foods, and include strawberry-iced cupcakes, cookies, crumpets, cakes, doughnuts, corn muffins and scones.
Sports Drinks
Sports drinks contain electrolytes to replace the sodium and other minerals lost during strenuous exercise. These drinks also contain sugar, which increases their impact on blood glucose levels. Kaye Foster-Powell, the author of "The Low GI Diet Revolution" and "The New Glucose Revolution for Diabetes," developed a glycemic index table with 750 foods. Foster-Powell's table indicates that the glycemic index of sports drinks ranges from 61 to 111, with two out of four brands exceeding a GI of 100. This table originally appeared in a 2002 issue of "The American Journal of Clinical Nutrition."
Refined Grains and Starches
White bread and foods made with refined grains have higher GI values than foods made with whole grains. One large slice of white bread has a glycemic index of 73, according to the Linus Pauling Institute at Oregon State University. Cornflakes have a GI value of 81 for a 1-cup serving. Starchy foods, such as potatoes, also have high GI values. One baked potato has a glycemic index of 76.
Fruits
Although fruits contain important vitamins and minerals, some fruits have high GI values. Foster-Powell's glycemic index table indicates that watermelon has a glycemic index of 103. The glycemic value of bananas depends on their growing location. A banana produced in the United States has a GI of 73, while a banana grown in South Africa has a GI of 100. Other high-GI fruits include dried dates, dried figs, papayas, raw pineapple and raisins.
Soft Drinks
Regular soft drinks contain sugar and sugar substitutes, which means they affect blood glucose levels. One serving of sugared cola has a glycemic index of 90, while a serving of orange soft drink has a glycemic index of 97, according to Foster-Powell. Fruit and vegetable juices still have sugar, but some have lower GI values than soft drinks. Carrot juice has a glycemic index of 61, and unsweetened apple juice has a glycemic index of 53.
