Glycemic Index, Load, and Impact: What's the Difference?

by Kate Itrich-Williams July 12, 2019

KNOW Better Sweets

Take a look at our shop or recipe collection and you'll see that we talk a lot about the fact that our foods, even all of those delicious sweets pictured above, have a low glycemic impact, or that they rank low on the glycemic index. But unless you're well-versed in these topics, you may not know what they actually mean. 

So to help you better understand what you're eating, we're breaking down what the glycemic index actually is, and what it means to say a food has a low glycemic load and a low glycemic impact.

Glycemic Index

Simply put, the glycemic index (GI) is a zero to 100 ranking of foods containing carbohydrates. A food's GI indicates how quickly the carbohydrates in the food are digested and released as glucose into the bloodstream. Foods with a GI of 55 or less are considered to have a low GI, foods with a GI of 56 to 69 are considered to have moderate GI, and anything that hits 70 or above is considered to have a high GI. 

Low GI and blood glucose graph

To give you a few examples, you'll find white bread and high fructose corn syrup way at the top of the GI (no surprise there). Near the bottom are foods like carrots, beans, and nuts. Again, not a big surprise.

While GI is useful as a comparison tool for various carbohydrate-containing foods, it also has its limitations. GI rankings are determined by the body's response to eating a food alone and on an empty stomach, which often doesn't happen in real life. While it's perfectly common to eat snack foods on their own, when was the last time you ate just carrots for dinner? 

These rankings are also not necessarily based on realistic serving sizes; rather they are based on a serving of each food that contains 50 grams of carbs minus the fiber. A common example given for this discrepancy is watermelon, which has a high GI around 72. However, to get to 50 grams of carbs in watermelon, you've got to eat 5 cups of the stuff. Of course eating that much watermelon would send your blood glucose soaring.

Instead, to see the true effect of eating a realistic amount of common foods, it is helpful to look at another measurement tool:

Glycemic Load

The glycemic load (GL) is based on the GI, but has a little more math involved. It accounts for real-life serving sizes by taking the carbohydrate count for a serving of said food, multiplying it by the food's GI, then dividing by 100.

This is useful because some foods may rank high on the glycemic index, indicating a high level of easily digestible carbohydrates available, but will have a low glycemic load since the actual serving size is relatively small. 

Foods with a GL under 10 are considered low-GL, those between 10 and 20 are moderate, and anything above 20 is considered to be high.

If we return to the watermelon example, and assume a 120 gram serving size (a little less than a cup), you'll end up with a GL of 4, which is quite low. Eat a little more and the GL goes up, but, again, you'd need to eat a bunch in order to hit a high GL.

But as much fun as it is to look at numbers all the time (sarcasm), there is another, more general way to analyze the way foods affect blood sugar:

Glycemic Impact

Glycemic impact takes into account both the GI and GL levels, as well as overall amounts of carbohydrates in foods. Glycemic impact isn't referred to using number values; foods are low-, moderate-, or high-impact.

Besides the fact that it is often easier to parse the impact of broad categories of foods instead of looking at particular numbers, looking at glycemic impact can also be helpful because it includes foods that contain little to no carbohydrates at all. As mentioned above, GI rankings are only given for foods that contain carbohydrates, so you can't rank things like steak or chicken on such as scale. Adding proteins and fats into a meal will decrease the meal's overall glycemic impact.

Building a dietary lifestyle around low-impact products such as KNOW Better Slices, buns, and cookies, along with healthy recipes, doesn't have to be super difficult. And we're here to help! Try out some of the recipes below, and be sure to consult our blog for more tips, tricks, and advice.

Instant Pot Pulled Pork Sandwiches
Simple Indoor Turkey Burgers
Chocolate Chip-Almond Keto Cookies
Grain-Free Carrot Cake



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