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What You Should Know About Foods’ Glycemic Index and Glycemic Load

by Cheryl Forberg, RD on June 29, 2012

We’ve been hearing a lot about keeping your blood sugar steady and the importance of following a low glycemic eating plan. Two common scales can give you information about how quickly foods will affect your blood sugar: the glycemic index and the glycemic load.

The glycemic index (GI) tells you how rapidly a carbohydrate turns into glucose in your body. One drawback is that it doesn’t tell you how much carbohydrate a specific food contains. Thus, the GI for a food is the same, regardless of portion size. For example, a tablespoon of honey and a cup of honey have the same GI. So just because a food ranks high in GI doesn’t always mean that it will raise your blood sugar level rapidly.

The glycemic load (GL), however, also takes into account a food’s available carbohydrates, which provide energy, like starch and sugar (so it excludes fiber). The GL measures the effect of a food’s GI multiplied by its available carbohydrate content in a standard serving; thus, it is a more realistic measure of the food’s potential to raise blood sugar. The glycemic load of honey, for example, is based on the serving size.

Some research says that high GLs may put you at risk for disease. The general principles of this idea should be considered when you’re making food choices, especially if you’re overweight or have pre-diabetes or a strong family history of diabetes.

If you don’t fall into one of those categories, monitoring GL is not as important from day to day. If you’re following the eating recommendations I’ve been posting , you can be certain that most of your food is loaded with fiber and on the lower end of the GL range (with the exception of some an occasional sweetener or dessert).

At some times, you might actually benefit from a high-GL food. For example, you’d want to reach for a high-quality higher-glycemic food before a workout to fuel your muscles. You’ll regain your energy and feel refreshed faster.

Below is a list of the glycemic index and glycemic load of common foods. When referring to the list, keep in mind that:

■ Low GI = 55 or less ■ Low GL = 10 or less
■ Medium GI = 56–69 ■ Medium GL = 11–19
■ High GI = 70 or more ■ High GL = 20 or more