Glycemic Index? Not So Fast

If you’re a regular ETR reader, you already know how important the glycemic index is to make sure you’re eating well. But there’s a big problem with using the glycemic index as a guide to eating: It doesn’t take into account portion size. Glycemic load – a far more useful number – does.

The glycemic index measures your blood sugar response to a “standard” serving of 50 grams of digestible (non-fiber) carbohydrate. Great. But the real world of actual portions presents a much different picture. Some carbohydrate foods have way less than 50 grams in a serving, while many typically have a lot more.

Enter the glycemic load, a formula that multiplies the glycemic index by the number of grams of carbs in a typical portion (and then divides the result by 100, in case you’d like to do the actual math). Because the formula for glycemic load takes into account real-life portion sizes, it gives you a much better idea of what a food is doing to your blood sugar.

Take spaghetti and carrots, for example. The glycemic index of 50 grams of spaghetti is only “moderate,” but you’d be hard-pressed to find someone who eats just 50 grams of spaghetti. The glycemic load of spaghetti is humongous. And while the glycemic index of 50 grams of carrots is “high,” you probably wouldn’t eat 50 grams of carrots. (There are only three grams of carbohydrate in a single carrot.) Carrots have a high glycemic index- but a very low glycemic load.

Using the glycemic index is a great start in learning about the impact of food on your blood sugar. But glycemic load is even better, because it takes into account what you’re actually likely to eat.

It’s easier to find the glycemic index of a food than the glycemic load, but you can find both at Alternately, you could ignore the entire glycemic numbers game and just follow this simple rule: When it comes to sugar, less is more, zero is better.

About the Author: Dr. Jonny Bowden is a nationally known expert on weight loss, nutrition, and health. He’s a board certified nutritionist with a master’s degree in psychology, and the author of the best-selling book, The 150 Healthiest Foods on Earth. For more information, go to