Glycemic load calculation on a paper with a pen and a calculator beside
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Glycemic Load vs Index: Which is Better for Managing Diabetes?

We all know how important blood sugar regulation is when you have type 2 diabetes… For people with diabetes, the terms glycemic index and glycemic load are probably pretty familiar. However, there is often some confusion about the difference between glycemic load vs index and how each of these measures comes into play for diabetes management.

Glycemic load calculation on a paper with a pen and a calculator beside

By the end of this article, you will understand the difference between glycemic index and glycemic load, how to use these measures for better blood sugar balance, and how much they actually matter when it comes to managing diabetes. Ready? Let’s dive in!

What is glycemic index (GI)?

Most people have at least heard of the glycemic index (GI) before… but do you actually know what it means? The GI is essentially a numbered ranking of the impact on blood sugar of carbohydrate-containing foods when compared to pure glucose (sugar).

The glycemic index scale is ranked from low to high impact on blood sugar from 0 to 100. Pure glucose is ranked at 100 on the GI as it has the strongest impact on blood glucose (aka blood sugar) levels. 

What does glycemic index mean for blood sugar management?

Knowing the GI of a food can help you make an educated decision on which types of carb-containing foods would be better choices to help control your blood sugar levels. In general, following a low glycemic index diet can definitely help you better control your blood sugar levels.

Foods are classified based on their GI score in the following way:

  • Low glycemic foods: 55 or less
  • Medium glycemic foods: 56-69
  • High glycemic foods: 70+

High glycemic foods are the carbohydrate-containing foods that digest the quickest, such as refined carbs and sugary candy. Foods that are packed with fiber, fat, and protein tend to digest more slowly, which means they rank lower on the GI. 

It is important to know that there are some foods that don’t have a GI score because they don’t contain any carbs. This means that meats, eggs, oils, herbs, and spices, which don’t contain carbohydrates, don’t have corresponding GI scores.

Another important thing to note is that the glycemic index of a specific food can actually change. Factors including ripeness, the cooking method, the type of carbohydrate/sugar present, and the amount of processing can drastically change the GI score of a food. A good example of this is that an under-ripe banana has a GI of 42, while a ripe banana scores at 51. 

How to find the glycemic index of foods

A notebook with Glycemic index calculations and a green apple and a pair of glasses beside

Figuring out the glycemic index of the foods you want to eat can be done most easily by searching an online database

Remember, some foods don’t have a GI score because they don’t contain any carbohydrates, like meats and oils. In order to be found on the GI scale, the food must contain carbs/sugars.

What is glycemic load (GL)?

Glycemic load (GL) is similar to glycemic index in that it ranks foods based on their ability to raise blood sugar levels. The important difference between GL and GI is that GL actually takes into account the portion of food consumed, making GL a more accurate representation of blood sugar response.

What does glycemic load mean for blood sugar management?

Knowing the GL of a food can help you make better decisions to maintain balanced blood sugar levels. Similarly to GI, the GL score increases as the impact on blood sugar increases.

The glycemic load scale is:

  • Low glycemic load = 0-10
  • Medium glycemic load = 11-19
  • High glycemic load = 20+

Understanding GL can help you plan specific portions of carbs that are less likely to spike your blood sugar. This tool can also come into use when you are trying out new foods to estimate the impact it will have on your blood glucose. 

How to calculate glycemic load

Notes with calculation formula for glycemic load with an marker on the notes and an apple and calculator beside

Luckily, calculating the glycemic load of a food is pretty simple. Take the grams of carbohydrates in the portion of food you consume and multiply that by the glycemic index of the food, then divide by 100. 

The equation for glycemic load looks like this: GL = (grams of carbs x GI) / 100

Let’s run through a quick example using a medium ripe banana, which contains 27 grams of carbohydrates. Remember that a ripe banana has a GI of 51. 

GL of a medium ripe banana = (27 grams carbs x 51 GI) / 100 = 1377/100 = 13.77

This GL score ranks a medium ripe banana as a medium glycemic load food and thus has a moderate impact on blood sugar levels.

This equation for GL shows us something extremely important. You can eat a little bit of a high GI food and a lot of a low GI food and end up with the same glycemic load. This fact perfectly exemplifies why using GI is not the full story when it comes to blood sugar impact.

Understandably, most people aren’t going to want to spend time doing calculations to determine the GL of their foods. You can use the same online database mentioned above to research foods for their corresponding GL.

Glycemic load vs index: which is better?

So, what’s the verdict? If you said glycemic load, you’ve definitely been paying attention! Glycemic load is an overall better measure because it takes into account more context than glycemic index does. By definition, the glycemic load takes into account both the glycemic index and portion size of a specific food. 

The serving size of food consumed absolutely matters when it comes to blood sugar impact. In general, the bigger the serving of a high glycemic food means more sugar consumed, which means higher likelihood of blood sugar spikes.

Downsides of GI and GL

Various healthy foods on a table, waffle with fruit, salad, oatmeal and honey

While both GI and GL are useful measures for comparing foods based on their ability to impact blood sugar levels, there are definitely downsides that make these measures imperfect.

The biggest downside of the glycemic index is that it is based on eating a single food and leaves out the context of portion size and impact of food pairings. While it is definitely common to eat some foods by themselves, most meals do not consist of a single food. Many times, eating just a little bit of something won’t impact your blood sugar much – but using the GI scale may lead to think the opposite is true.

Although glycemic load is a better estimation of blood sugar impact because it takes portion sizes into account, there are some other factors that can impact blood sugar that this measure ignores. 

Neither GI or GL takes into account how food pairings can impact blood sugar response. Eating foods that are high in fiber, fat, and protein alongside a high-carb/high GI/GL food can mitigate the blood sugar response by slowing down the digestion and absorption of sugars into the bloodstream.

Some other variables that are completely ignored by GI and GL which also impact blood sugar include:

  • Time of day 
  • Activity levels (more activity = lower blood sugar)
  • Stress levels during meals (more stress = higher blood sugar)
  • Individual differences in reaction to carbohydrates/sugars in foods

As humans, we aren’t living in a vacuum consuming just one food at a time, so it is extremely important to take all of the variables above into consideration when estimating the impact of foods on blood sugar. 

The absolute best practice to fully understand how certain foods impact your individual blood sugar response is to use a blood glucose monitor to assess the difference in blood sugar before and after meals.

The bottom line on glycemic index vs glycemic load

When comparing glycemic index and glycemic load, there is a clear winner (GL) purely because it takes more context into account. However, neither GI nor GL will accurately depict blood sugar responses to foods since they leave out some critical context, and therefore, do not paint the full picture.

While neither of these are perfect measures, the GI and GL are still useful tools that can help you plan better meals for blood sugar balance when you have diabetes. Just remember that the best way to gauge your blood sugar response to foods is through testing your blood sugar levels before eating, then again 1 to 2 hours after a meal.

If you’re consistently testing your blood sugar levels and are following the diabetes plate method, tracking the GI and GL of all of your foods is not 100% necessary. Just think of these measures as another tool in your toolbox that can help you with your diabetes management.

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