Glycemic Index and Glycemic Load - what's the difference?

Glycemic this and glycemic that. We hear about it but do we understand the difference between the two?

In general, diets that are high on the glycemic index (GI) and high in glycemic load (GL), tend to increase the risk of diabetes and heart disease. Neither is good. Here is a quick reference of sugars, carbs and how they affect your blood sugar levels.


Glycemic Index (“how fast”)

The most common of the two terms is “glycemic index” (GI). As the name suggests, it "indexes" (or compares) the effect that different foods have on your blood sugar level. Then each food is given a score from 0 (no effect on blood sugar) to 100 (big effect on blood sugar). Foods that cause a fast increase in blood sugar have a high GI. That is because the sugar in them is quickly processed by your digestive system and absorbed into your blood. They cause a “spike” in your blood sugar.

So, you can probably guess that pure glucose is given a GI rating of 100. On the other hand, chickpeas are right down there at a GI of 10.

Low GI is anything under 55; moderate is 56-69, and 70+ is considered a high GI food.

Remember, this is a measure of how fast a carbohydrate containing food is digested and raised your blood sugar. It's not a measure of the sugar content of the food.

How the carbohydrates in food affect your blood sugar level depend on other components of the food. Things like fiber and protein can slow the release of sugar into the bloodstream, and this can make even a high-sugar food, low on the GI scale.

So, lower GI foods are better at keeping your blood sugar levels stable because they don't increase your blood sugar level as fast.


FUN FACT: Can you guess which food has a GI of higher than 100? (Think of something super-starchy) White potatoes! They have a GI of 111.



Glycemic Load (“how much”)

The glycemic load is different. Glycemic load (GL) doesn’t take into account how quickly your blood sugar “spikes”, it measures how high that spike is. Basically, how much the food increases your blood sugar.

GL depends on two things. First, how much sugar is in the food. Second, how much of the food is typically eaten.

Low GL would be 0-10, moderate GL would be 10-20, and high GL would 20+.