Part I

The glycemic index (GI) is a very hotly debated topic in the world of nutrition. Unfortunately, most folks aren’t even aware of how it’s measured or what it means when it comes to health and disease prevention. To clarify the issue, let’s briefly review this assessment tool here in Part I and then look at some research regarding its use in Part II.

The GI is basically a measure of how carbohydrate foods affect blood glucose levels. Specifically, it represents the “area under the curve” when plotting the blood glucose elevations of a test food measured over two hours. The values of the test food, taken in 15-minute increments, are graphed and then compared to a reference food, which is most often glucose. The GI is measured on two or three separate occasions for each individual, with the “official” value representing the average obtained from 8-10 different people. Glucose is given a score of 100, with all other foods having a lower score. Foods with a GI less than 55 are considered low, while foods above 70 are considered high. Foods that fall between these values are intermediate or medium. It is important to remember that there are actually two GI lists, one using glucose and the other using white bread as the reference food. If you see numbers that differ significantly, it’s likely that you’re making comparisons using both lists.