The glycemic index (GI) is a system of measuring how quickly foods we eat, particularly carbohydrates, affect blood sugar levels. The higher the value of a food on the glycemic index, the more quickly it will raise blood sugar. It is calculated based on consuming 100 grams of the food.

The GI was meant to be a basic useful concept for those with diabetes and is now a trendy term when talking about supposedly “good” or “bad” carbohydrates. However, the GI is misleading for several reasons.

For one, the glycemic index only rates foods in isolation. In reality, we almost always combine foods when we eat and this will change the GI. Peanut butter may be rated, but trying to determine the GI rating for something as simple as a peanut butter and jelly sandwich can prove very difficult even though we know the numbers for the individual components.

In addition, not all carbohydrates are created equal. Fructose, for example, has a low GI rating, but it can cause insulin inefficiency and other health problems. If we relied solely on GI, fructose would appear desirable even though we know it is not.

A related concept, glycemic load, is much more useful because it takes into account the effect of the entire meal, both in terms of the type of food eaten and the amount consumed.

Share This