Glycemic Index and the Glycemic Load 101: A Nutritionists Look

The Glycemic Index (GI) Diet has been largely marketed as a weight loss diet or a diet for diabetics, but where did it’s theories originate from and why is it so important that we all know about this so-called ‘glycemic index’ and ‘glycemic load’? Keep reading to discover how you can add this relatively simple concept to your daily routine to Be Healthy & Feel Fabulous!


Glycemic Index Revolution:

Firstly, let me point out that Canadian researchers, Dr. David Jenkins and his team at the University of Toronto were the first to develop the Glycemic Index, introducing to the world of diabetic dietary management: The New Glucose Revolution.

It’s comprised of true measurements of changes in blood glucose levels after ingesting a particular food. What this means is that GI scores are used to rank foods.

All foods are compared to a standard. When creating the list at the University of Toronto, Dr. Jenkins compared foods to cream of wheat looking at how glucose and insulin levels were raised. Different labs (and different GI Diet books) use different standards to equal 100, such as white toast, pure glucose and others. In order to determine a food’s ‘GI’ score, each and every individual food is compared to the standard.

When we consume foods that spike our blood sugar, the body freaks out. Let me give you an example. When we eat sugar it is broken down into glucose in the body. This glucose is then floating around the blood stream trying to get into the cells so it can be used for energy. The problem is that to get into the cells it requires a key. When our pancreas senses glucose in the blood stream it releases something called insulin. Insulin is the key that opens the cells and let’s glucose in so it is no longer in the blood stream. If we eat foods that spike our blood sugar too quickly and too high it is difficult for the pancreas to keep up. When the glucose is in the blood stream for too long or if there is too much, problems can arise. Some examples of these problems include: increased stress levels, obesity, stroke, high blood pressure, heart disease, metabolic syndrome, hypoglycemia, diabetes, and even shuttling of proteins.

Therefore, the Glycemic Index measures the rate at which our food is converted into glucose (i.e. how quickly our blood sugar spikes).

How the Results of Each Food are Grouped:

—  100 +: extreme rise in glucose & excess insulin

—  70–100: rapid rise in glucose & insulin

—  40-69:  moderate rise in glucose & insulin

—   1 – 39: slow rise in glucose & insulin

—  “0”: no effect on blood sugar levels (e.g. water, fat)

What foods are allowed?

Typically, allowed foods have a GI score in the 0-69 range.

When we consume these foods we don’t have the massive increase in blood sugar which helps to prevent some of the problems of a high-glycemic diet that I listed above.

Therefore, it is helpful to know what types of foods fall in the various ranges so that you can aim to consume foods that result in a balanced steady blood sugar. If you go to the website you can type in various foods and find out their GI score.

There are three other important things to note about the glycemic index:

  1. The first is that the GI score is accurate when you are consuming a particular food on its own. As soon as you combine the food into a meal it changes the overall effect on your blood sugar at that time. Therefore, let’s say you consumed a higher glycemic index food. However, instead of eating it on its own, you eat it with a food that is higher in fat, or with other low glycemic foods. The overall result is that your blood sugar won’t spike as much as it would if you had eaten the food on its own. Therefore, the lesson here is that, in general, we should be reducing high-glycemic foods and we should also ensure we don’t eat high-glycemic foods on their own.
  2. The second important thing I wanted to mention is that, although it is recommended we avoid high-glycemic foods, there is actually a time when consuming them is a good idea. Having a higher-glycemic food, such as a banana with your protein shake after a great workout, helps shuttle protein and nutrients into the muscle cells. This is thanks to that little insulin spike from your healthy high-glycemic food choice. Just make sure you keep it healthy and as clean as possible. Stay away from the refined processed stuff as it may be high on the glycemic index but it completely lacks nutrition (which is also important post workout). Being a certified personal trainer I’m always teaching my clients about this and the importance of understanding how to maximize muscle recovery and get insulin working FOR them.
  3. The third is that whether a food has a high or low GI score is not the only factor that should be used for determining if a food is healthy. To give you an example, a junk food that is high in fat and artificial sweeteners will rank low on the glycemic index. However, that doesn’t mean it is a healthy food. Using the glycemic index is only one tool in the toolbox to help you choose healthy foods.

Glycemic Load:

The glycemic index is a great way to understand how foods affect insulin and glucose levels in the body (how fast they spike), but the glycemic load makes the picture even clearer. In a nut shell, the glycemic load measures the total amount of glucose provided by a specific food. Therefore, if the glycemic load is high, that means that the food will produce a lot of glucose in the body. If the score is low, it means that particular food doesn’t actually supply much glucose to the body.

If we only look at the glycemic index we aren’t getting the whole picture. Take watermelon as an example. Although watermelon has a high GI, there isn’t a lot of carbohydrate in a serving, thus making watermelon’s glycemic load relatively low.

Diana Rodriguez’s article: The Lowdown on Glycemic Load (medically reviewed by Christine Wilmsen Craig, MD) talks about the glycemic load and emphasizes the need to look at the whole picture of the foods we are consuming – a principle I’m all about!  Thanks to glycemic load, we now have a new way to assess the impact of carbohydrate consumption, accounting for the glycemic index and how much carbohydrate is in a serving of a particular food (making sure that the fiber content is accounted for).

How to Find Glycemic Load:

Finding out the glycemic load for a particular food is easy. Keep reading.

For those who want to be able to calculate it themselves, here’s the equation:

Glycemic load = Glycemic index divided by 100 multiplied by its available carbohydrate content (i.e. grams of carbohydrate minus grams of fiber)

Here’s how each calculation is ranked:

—  High GL = 20 or more

—  Medium GL = 11-19

—  Low GL = 10 or less

Example: watermelon

—  Relatively high glycemic index of about 72

—  Serving of 120 g has 6 g of available carbohydrate per serving

GL = 72/(100 x 6) = 4.32, rounded to 4 (LOW)

Skip the mathematics and get straight to the categorized list of foods glycemic load:

Be sure to check out Diana Rodriguez’s article: The Lowdown on Glycemic Load, to get a quick preview of a glycemic load reference list with many common foods to let you know which are low, medium, and high.

Learn More:

You can also pick up a book with all the calculations completed for you to take with you to the grocery store and to use when planning your meals. Here’s two to get you started:

1)      The Glycemic Load Counter  by Mabel Blades

2)      Glycemic Index and Glycemic Load of Foods by DietGrail Publisher

Now you can be an educated consumer and be your own ‘food undresser’ by comparing foods using the glycemic index and the glycemic load, and exercising mindfulness when choosing what foods we put into our bodies.

If you found this article beneficial and want to share it with your friends, family and coworkers, please help us spread this information by sharing it on facebook and twitter. I would love to hear your comments and experiences. Feel free to leave a comment below in the comment box.


Blair, Louise. 2005. Low GI CookBook.  Octopus Publishing Group Ltd: London.

Colbin, Annemarie. 1986. Food and Healing: How what you eat determines your health, your well-being, and the quality of your life. The Random House Publishing Group: Toronto,  Canada.

Hoppe C, Mølgaard C, Vaag A, Barkholt V, Michaelsen KF. 2005. High intakes of milk, but not   meat, increases insulin and insulin resistance in 8-year-old boys. Eur J Clin Nutr.: 59(3):393-8.

Rodrigues, Diana. 2012. The Lowdown on Glycemic Load.  <  >

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