Glycemic Index vs. Glycemic Load

If you are someone who labels carbohydrates as “bad” or you are hesitant to eat a potato, then this information is for you.

Below we dive into glycemic index and load, the problems we experience with each, and how you can begin to conquer your nutrition. My hope is that you will have better understanding of these physiological markers while learning how to experience freedom and confidence in what you eat. 

(Note: People with diabetes should speak to their physician before starting a new diet.)

Glycemic Index

The glycemic index (GI) is a measure of how quickly, and significantly, a certain food can raise your blood sugar levels. The GI measurement compares 50g of a specific food’s carbohydrates to 50g of pure glucose (100% sugar) to examine the rate at which the food increases blood sugar levels. Generally, the less processed food is, the lower GI it will have since it takes longer for the body to digest.

Low – up to 55 | Medium – 56 to 70 | High – over 70

If food is ranked high on the GI scale, this tells us that it has readily available carbohydrates for fast absorption.

The Problems with Glycemic Index

While the glycemic index is an interesting physiological response to food, this measure doesn’t give us the whole story.

1 – Glycemic index assumes that 50g of carbohydrates are being eaten by itself. This isn’t how we should be eating our meals. When was the last time you sat down to dinner and exclusively ate a potato without toppings? We eat our carbohydrates with water, fats, protein, and vegetables – all of which lower the rate of digestion.

2 – The GI of a food isn’t constant and will change based on how food is prepared, what you eat it with, the time of day, how your body reacts to certain foods, and how active you’ve been that day. For example, if a carbohydrate contains or is eaten with healthy fats or an acid, the food will be digested slower and will gradually raise blood sugar levels. Foods like vinegar, lemon juice, and sourdough bread all contribute to lowering the GI of a meal.

3 – A food’s glycemic index is determined by a standard carbohydrate serving of 50g, not an actual serving size. Food that is ranked high on the GI scale may have readily available carbohydrates, but would require a huge serving size to elicit the assumed spike in blood sugar.

For example, 50g of sugar is easy to come by (1 chocolate bar and 1/4 can of pop is 50g of sugar/carbohydrates), but it takes 5 cups of carrots to reach 50g of carbohydrates. This reason alone is why glycemic index is considered an unfair measurement.

Glycemic Load

Like glycemic index, the glycemic load (GL) looks at how quickly carbohydrates are digested and how those foods affect our blood sugar levels. Unlike GI, glycemic load takes the serving size of food into account, which makes it a more realistic measurement tool.

Low – up to 9 | Medium – 10 to 19 | High – over 19

The Problem with Glycemic Load

While GL is a slightly better measurement than GI, we still face the same problem with its accuracy in determining how it will impact our blood sugar levels.

Glycemic load assigns a number to food based on the assumption that we will be eating that food on its own. The GL changes based on what the food it is eaten with, time of day, how it was cooked, the micronutrient content, etc.

Low – Green | Medium – Orange | High – Red

Looking to a chart every time you want to eat or living in fear that you’re raising your blood sugar, is no way to live. Glycemic index and load are both interesting physiological responses, but they don’t determine the healthfulness of a food.

For an example of this, look to the chart above. We can all agree that a potato is healthier for you than a snickers candy bar, but based on GI and GL, it would appear that the opposite is true. What GI and GL can’t show you is that the potato is high in vitamin C and B6, fiber, potassium, magnesium and antioxidants, all while being lower in calories than the candy bar.

The Best Option

Aim to eat low- and unprocessed carbohydrates 80% of the time to help your body feel and function at its best. If you’re concerned about which type or what carbohydrates to eat, don’t be. When you eat food as close to its natural form as possible, you are eating it the way is was intended to be. These unprocessed foods fuel your body and brain while providing you with fiber (to naturally slow digestion), and essential micronutrients and vitamins.

Related: Stop Dieting and Start Succeeding

If I HAD to choose between glycemic index and glycemic load, I would recommend glycemic load only because it does take serving size into account. That said, if there was a measurement that could take time of day, digestive efficiency, micronutrients, etc. into account, I would 100% recommend that system.  GL and GI can’t give us the whole story behind our food and “eating by numbers” can become an unhealthy obsession.

If you want to reach your health goals, give your body the macro- and micronutrients it needs, drink water and be patient because you WILL reach them.


What did you think about this post? Let me know in the comments below. 


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