## Glycemic Load:what is it? when does it matter?

You may have heard the buzz out there about Glycemic Load in relation to weight loss and type 2 diabetes management. This article will give you a short and simple description of what glycemic load is… and what it isn’t: Is it the same as Glycemic Index? (No) Is there a practical application for the concept of Glycemic Load? (Well, that depends…)

## To review…

The Carb Content of a given food determines how much that food will raise blood glucose.
The Glycemic Index (GI) of a given food describes how quickly it will raise blood glucose.

However, there is a related concept which incorporates both of the above factors (carb content and glycemic index value); that concept is Glycemic Load (GL).

The Glycemic Load (GL) of a given food refers to how much blood glucose will rise after eating a certain food, PLUS how long it will stay high. You can think of GL as referring to the degree of force, or “load” a given food puts on our bodies in terms of processing and dealing with glucose. From another angle, Glycemic Load can be thought of as the amount of carbs in a food, adjusted for its glycemic potency.

For example, from a table of Glycemic Load values, we find that a potato with 15 g of carbs has a GL of 12, while an apple with an equivalent 15 g of carbs has a GL of 6; the potato has twice the Glycemic Load as the apple. Though both foods have the same carbohydrate content in this case, the apple exerts less “force” (lower Glycemic Load) because of its lower Glycemic Index value.

The scales could be “tipped” in the other direction, however, if the portion of potato eaten was substantially smaller than the portion of apple eaten: one bite of potato will have a lower Glycemic Load than a whole apple, as the substantially larger carb content of the apple will “overpower” the high Glycemic Index of the potato.

In short, it makes intuitive sense that both of the dual concepts of glycemic index and carb content will affect blood glucose, and that the higher a meal is on either one of these components, the greater the effect on blood glucose. Here, we are simply expressing this interplay as “Glycemic Load”.

Like Glycemic Index values, Glycemic Load values can be categorized as Low, Medium and High. However, since Glycemic Load (GL) is related, but not identical, to Glycemic Index (GI), the numbers associated with GL categories are different from those associated with GI categories.

Low Glycemic Load =10 or less
Medium Glycemic Load = 11 – 19
High Glycemic Load = 20 or higher

Returning to the example above, the potato with a Glycemic Load (GL) of 12 is considered a Medium Glycemic Load; the apple with a Glycemic Load (GL) of 6 is considered to have a Low Glycemic Load.

(Note: Sometimes Glycemic Load (GL) values are listed along with Glycemic Index (GI) in a table of GI values – if you are interested in exploring the specifics, we have found “The New Glucose Revolution” by Dr. Jennie Brand-Miller (primary author) to be very helpful.)

## How is Glycemic Load Calculated?

When calculating the GL of a certain food, the Glycemic Index of a given food is multiplied by the Carbohydrate Content of a given serving size of that food, and the result is divided by the number one hundred. Mathematically, that formula looks like this:

Glycemic Load (GL) = Glycemic Index (GI) x Carb Content
100

Returning to the example above…

One medium apple (with skin) has 15g of available carbs, and a low GI value of 38, resulting in a Glycemic Load (GL) value of:

38 x 15
100

= (5.7 rounded to the nearest whole number) = 6

One small baked russet potato (with skin) that has 15g of available carbs, however, has a high GI value of 77, resulting in a Glycemic Load (GL) value of:

77 x 15
100

= (11.6 rounded to the nearest whole number) = 12

So two foods, both with the same carb content (15g) can have two very different Glycemic Load values.