Just when you started to get a handle on the glycemic index (GI) of foods, there's another value to grasp — glycemic load (GL). The GI ranks specific carbohydrates from zero to 100, based on the rate in which they affect your blood sugar levels. A GI of 1 to 55 is low, 56 to 69 is medium, and 70 to 100 is high — these high-ranking foods should be limited.
Glycemic load measures the blood-sugar-raising power per serving of food. Here's the lowdown on the equations used to figure the load. First you multiply the GI of a food by the amount of grams of carbohydrate in a specific serving, and then that number is divided by 100. A glycemic load of 10 or less is low, 11 to 19 is medium, 20 or more is high. If you add up the glycemic load amounts for your entire day, a total GL amount of 80 or less is considered low. Your daily GL shouldn't exceed 120.
Both measurements are useful. Glycemic load helps you select appropriate portion sizes, while glycemic index helps you differentiate between good and bad carbohydrate choices. The lower each number, the less it affects blood sugar levels.