Simplifying the Glycemic Load

The foods that we eat all affect our blood sugar level. But, as you probably know, some foods affect our blood sugar more severely than others. For diabetics, eating foods that have a gentler effect on blood sugar levels is important for managing/controlling their disease. For those who don’t have diabetes, your blood sugar is still important—why wouldn’t you want to eat foods that will help prevent you from developing the disease?

There are two numbers that have been developed to help people understand how foods affect their blood sugar. The glycemic index (GI) is a number showing how quickly a food will be converted to sugar and cause a person’s blood sugar to rise. Foods with a low GI will cause a small rise in blood sugar while foods with a high GI will cause the blood sugar to rise quickly (often called a ‘spike’). Generally, a food with a GI below 55 is considered to be low-glycemic, while foods over 70 are high-glycemic.

Introducing the Glycemic Load

The glycemic load (GL) is a number derived from the GI and is a relatively new way to track blood sugar. To calculate the glycemic load, you multiply the GI of a food by the amount of carbohydrates per serving and then divide by a hundred.

Let’s look at an example. A typical energy bar has a GI of around 70 (this number varies quite a bit depending on the ingredients). To find the amount of carbohydrates per serving, check out the nutrition facts provided on the box or package. You’ll see that the bar has 45 grams of carbohydrate per serving. Do some quick math: 70 x 45 = 3,150. Divide the product (3,150) by 100 to get your GL. In our case, the GL is 31.5.

This formula used to calculate the GL means the number you get is reflective of portion size. Generally, serving with a GL of 10 or lower is considered low-glycemic. (This means that the GL in our energy bar is sky high. In fact, it’s worse than most candy bars.)

In many ways, the GL is a more useful number than the GI because it tells us how much a food will actually affect our blood sugar after they eat it (not just the rate that the food is converted into sugar). Even if a food has a high GI, its GL may actually be relatively small. For example, potatoes have a GI of 78 (high-glycemic), but the GL could actually be quite low. Basically, the potato will quickly be converted to sugar, but the overall sugar levels may be rather small.

Finding a Food’s Glycemic Load… Practically

For the rest of this article, we will concentrate on the glycemic load (GL) and how to understand the numbers. But first we need an easy way to find a food’s GL. Well, I’d like to let you know about a website, nutritiondata.self.com, that is an excellent source of information about the foods we are consuming. One great thing about this site is that they provide the estimated GL for every food in their vast database.

Because it may sound a little complicated, I’ll quickly explain how to use these numbers. Let’s find a food.

Navigate to their website and use the search bar at the top of the page to pull up a food—it may take a little practice to find what you want right away. Usually, the more specific you can be the better. For example, if you search ‘potato,’ you’re going to end up with a ton of entries (198 actually) ranging from an “Arby’s side order” to “sweet potato leaves”. For this search to be useful, we’ll have to be a little more specific. Now try searching, ‘potato boiled,’ and 10 results will appear. This is a lot more manageable.

From here, you’ll have to choose the entry that fits best. For our purposes, let’s choose ‘Potatoes, boiled, cooked in skin, flesh, without salt.’ Clicking on the entry will provide you with a host of nutrition information. All of the information is useful, but for the purposes of this article, we are concerned with the box called ‘estimated glycemic load’. You’ll see that this food has an estimated GL of 7 (depending on serving size).

What to Eat?

So what does that mean? Well, as the website reminds us, we should keep our total daily glycemic load below 100. Spend a little bit of time checking the foods that you tend to eat. You’ll be able to see which ones you should be cutting back on or eliminating. It won’t take too long for some patterns to start to emerge. Generally, the more processed a food is, the higher its GL will be.

For example, one cup of cooked medium grain white rice has a GL of 29. Simply switching over to brown rice will lower the GL by about 25%. A cup of cooked brown rice has a glycemic load of 22. Switching from all-purpose white flour to whole-wheat flour will lower the GL by a third. Over the course of a day, those amounts really add up!

Some people believe that, because fruits tend to have a high glycemic index, they should be avoided. But this is simply not the case. Natural sugars, such as the fructose found in fruits, digest much differently than products like refined, white sugar. For example, a cup of raw apples or watermelon has a GL of only 3. A cup of peaches has a GL of 5 and a cup of mangoes has a GL of 8. Although fruits contain a lot of sugar (fructose), their overall affect on glucose levels is quite small.

Besides this, vegetables all tend to have very low GLs. Nuts and seeds are also very low. Many, such as walnuts, almonds, peanuts, pecans, sunflower seeds, actually have a GL of 0 even when eaten in large quantities.

A Word of Warning

Now, before we go any further, I need to give you a warning. When evaluating a food’s GL, it is very important to keep an eye on the serving size. Consider this, a fortune cookie has an estimated GL of 5. Your average navel orange also has a GL of 5. So which one is better for your blood sugar? If you were just looking at the GL, you might conclude that these foods will have an equal effect. However, there is a little more we need to understand.

A fortune cookie only weighs about 8 grams. In contrast, your average orange weighs about 140 grams…17.5 times more than the fortune cookie. To properly compare these two foods, you’d have to look at one fortune cookie and about half of an orange section. When compared this way, gram for gram, the orange’s GL is much lower. So don’t let the numbers deceive you, be sure to check a food’s serving size. If you had to choose one of them for desert, the orange would be a far better choice.

Thankfully, the website we are using, nutritiondata.self.com, can easily be used to compare foods accurately. The serving size for every food on the website can be set at 100 grams.

There is just one other thing I should mention. The GL is basically a measure of carbohydrates. Just because a product has a small GL—or none at all—does not necessarily mean it is healthy. Drinking a cup of olive oil or eating a stick of butter will not raise your blood sugar, but your heart, arteries, and waistline won’t be happy. In these situations, use your common sense. Unless we are dealing with carbohydrates, the GL is not necessarily an indicator of a healthy food.

So there you have it, a simple tool to help you learn about, and manage your blood sugar. If nothing else, checking out the GL of different foods will give you yet another reason to eat a lot of fruits and vegetables. Fill up on those fresh, healthy foods. Besides helping you manage your blood sugar, they’ll ensure you’re getting great nutrition as well. 

Jon Ewald, MD

Jon Ewald grew up in Minnesota and has a love for the outdoors. He obtained his medical degree at Loma Linda University, graduating in 2020. He is currently completing his residency in Radiology at University of Pittsburgh.