Insulin resistance

How to use the glycemic index (GI)
and glycemic load (GL)

The glycemic index (GI) is an important nutritional tool that can help people keep their blood sugar in better balance. In simple terms, the glycemic index ranks foods numerically according to their potential to increase blood sugar and insulin levels. It’s a quantitative measure for how rapidly a set amount (50 grams) of a certain food is converted in the body into glucose (blood sugar), as compared to 50 grams of white bread, which has a GI of 100. Using the GI can theoretically keep blood sugar from spiking too quickly and overloading your cells with glucose. And over time, balanced blood sugar can help to prevent and reverse insulin resistance, the problem that lies at the core of metabolic syndrome and type 2 diabetes.

Generally speaking, a low-glycemic food has a GI of 55 or less; a GI of 56–69 is considered moderate; and a high-glycemic food has a GI of 70 or above. We’ve provided an abbreviated glycemic index chart below. Keeping in mind which foods fall under the categories of low, moderate, and high glycemic index may be all you need to make good food choices that keep your insulin levels steady.

Glycemic index versus glycemic load — strengths and limitations

Though it has many benefits, the value of the glycemic index as a tool remains somewhat controversial. In part, this is because the GI of a single food can vary depending on several things, including how it was grown, processed or prepared (see GI table below). In addition, each of us is physiologically unique, so how we respond to foods differs given our metabolic make-up, when and how much we eat, and how we combine our foods.

What’s more, there are inconsistencies in how the glycemic index is calculated. And some experts say that because the glycemic index is based on such a small quantity of food (50 grams) — less than the amount you’d typically eat — it understates the impact high-carb foods have on your blood sugar, while overstating the impact of low-carb foods.

To rectify this, some nutritionists have developed a calculation for glycemic load (GL) and recommend that it be used as a dietary guide instead of the glycemic index because it accounts for the amount of food you are consuming as well as the way you combine your foods.

To calculate the glycemic load (GL) of a food, divide the GI by 100 and multiply by the grams of carbohydrate in the serving size.

Getting a handle on the concepts of glycemic index and glycemic load can also help you see why combining the four food groups is a healthy way to eat, and why a scoop of ice cream, which has some protein and fat in it, has a lower GI and net glycemic load than a handful of Cheerios, which has little but refined carbs. That said, many women find the GI on its own to be a useful in gauging appropriate food choices and prefer it over other methods such as counting carbs. So while we recognize the shortcomings of the glycemic index, we continue to offer women information on how to use it simply because it can be helpful in keeping insulin resistance at bay.

Many women experience powerful cravings for high-glycemic index foods — particularly during times of hormonal fluctuation, such as premenstrually and in perimenopause. Since so many of us are surrounded daily with offerings of highly refined and processed foods, our willpower is constantly under siege! This is a problem that increases for us as we age, because a diet high in refined carbohydrates and high-glycemic foods can lead us down the path of inflammation and hormonal imbalance, to worsening insulin resistance, prediabetes and, ultimately, type 2 diabetes — and all the negative health consequences that go with it.

We encourage you to review our articles on insulin resistance to learn the value of all the tools you have at hand to make choices that benefit your unique physiology — and decide for yourself whether the glycemic index deserves a place in your toolkit.

The following chart is loosely based on the pioneering work of Jennie Brand–Miller and colleagues since the 1980’s. Keep in mind that this contains only a very narrow selection of foods; for a more comprehensive listing, you can refer to the International Table of Glycemic Index and Glycemic Load Values (2002).

Glycemic Index table

Low glycemic:	Low to moderate glycemic:	Moderate to high glycemic:	High glycemic:
barley black beans broccoli cashews cherries chickpeas grapefruit green leafy vegetables kidney beans lentils milk peanuts peanut butter pears plums soybeans strawberries tomatoes tomato soup wild rice plain yogurt	All-Bran apples brown rice carrots garbanzo beans grapes honey ice cream kidney beans navy beans oranges peas peaches pears pinto beans potato chips	bananas figs mangos potatoes (sweet and white) pineapple pita bread oat bran oat bread white rice raisins carrots brown rice kidney beans shredded wheat	bagels beets cakes Cheerios dates corn flakes pies pretzels refined durum wheat pasta jelly beans parsnips puffed wheat sweet corn white bread
Chart is loosely based on Foster–Powell, K., S. Holt, & J. Brand–Miller. 2002. International table of glycemic index and glycemic load values. American Journal of Clinical Nutrition, 76 (1), 5–556. URL: http://www.ajcn.org/cgi/content/full/76/1/5 (free full text; accessed 03.28.2007).

It’s also important to realize that just because a food ranks relatively low on the GI doesn’t mean it’s necessarily better for you than one that ranks high. Let’s face it, many foods today offer little but empty calories — a candy bar may rank below a sweet potato on the GI, but the sweet potato contributes way more in the form of micronutrients that compensate for its high sugar content. So pick and choose from the glycemic index chart with this thought in mind.

When it comes to the science of calculating which foods fall where on the glycemic index chart, we agree that more studies are certainly needed. But the benefit women can achieve by emphasizing low-glycemic index foods in their diet is great enough — especially those whose metabolic profile falls along the spectrum of insulin resistance — that we will continue to recommend and use it in guiding food choices.

Related to this article:

References & further reading on glycemic index and glycemic load

 

Last Modified Date: 05/26/2011
Principal Author: Marcella Sweet