Comparing the Glycemic Index to the Glycemic Load
6 of 9 in Series: The Essentials of Starting a Low-Glycemic Diet
Rather than limiting yourself strictly to foods low on the glycemic index, you can broaden your outlook to include the glycemic load. The glycemic load is based on the idea that a high-glycemic food eaten in small quantities produces a blood sugar response similar to the response produced by low-glycemic foods. The glycemic load breaks carbs down into the quantity you’d typically eat at one sitting, which can turn a high-glycemic food into a low-glycemic food. That’s good news because you don’t want to be too restricted in what you can eat.
The glycemic load takes into account the fact that the amount of carbohydrates vary in different foods (for instance, some fruits and vegetables have only 5 grams of carbohydrates whereas starches have up to 15 grams). It calculates the quality and quantity of carbohydrates at a meal.
Looking at portion sizes and carbohydrate grams can give you a better understanding of the glycemic load:
|Food Group||Carbohydrate Grams||Portion Size|
|Starches||15||1/2 cup pasta, 1 slice bread, 1/3 cup white rice|
|Fruits||15||1 small piece|
|Dairy products||12||1 cup milk, 1 cup light yogurt|
|Nonstarchy vegetables||5||1/2 cup cooked, 1 cup raw|
The amount of carbohydrates in a serving of a particular food depends as much on the portion size as it does on the food itself. So consuming 50 grams of carbohydrates (which is definitely more than one serving) will have a dramatic impact on your blood sugar. Take carrots, for example. Carrots have a high glycemic index when cooked (41 to be exact), yet they’re considered a nonstarchy vegetable. To consume 50 grams of carbohydrates in carrots, you’d have to eat 5 cups! Because the amount of carbohydrates in carrots is so low compared to their average portion size, the glycemic load of carrots is low as well.
On the other hand, a serving of instant white rice, another high-glycemic food with a glycemic index of 72, has around 15 grams of carbohydrates per 1/3-cup serving. To eat 50 grams of carbohydrates in instant white rice, you’d have to eat slightly more than 1 cup of rice — a fairly typical portion size for most people. This portion size means the glycemic load for instant white rice doesn’t change much from the food’s glycemic index.
The glycemic index compares the potential of foods with equal amounts of carbohydrates to raise blood sugar. The purpose of the glycemic load is to have a usable indicator of the glycemic index that takes portion size into account. Although adding glycemic load to the mix may cause the glycemic index of some foods, such as white rice, to remain the same, it opens up the door for enjoying more foods that may have a high glycemic index but a low glycemic load based on different portion sizes.