Understanding blood sugar control: Glycemic Index and Glycemic Load approach


If you have elevated blood sugar, it’s crucial to understand how different types of foods affect your health. A meal’s total amount of carbohydrates is the most critical factor for your blood sugar level after eating. How do you know the total amount of carbs when the ingredients vary drastically in the amount and the types of carbohydrates in them?

A while back, scientists came up with two ways to evaluate the carbs. First, they measured the Glycemic Index and Glycemic Load of foods and assigned a number to each ingredient. Then, they created long lists of foods ranked by those two factors. The lower the number, the better it is supposed to be for your blood sugar response. Sounds pretty good, right? 

Let’s dive in and learn more about these two measurements of foods and how you can apply them in your life.

Glycemic Index 

The Glycemic Index (GI) measures how quickly and how high blood sugar will increase after eating the amount of an ingredient that contains 50 g of carbs compared to eating 50 grams of pure glucose. For example, an average apple has about 15 grams of carbs. So you’ll need to consume 3.3 apples to get 50 grams of carbs and then compare it to 50 grams of glucose.

The higher the GI number, the quicker the food gets digested, and the faster the blood sugar levels rise. Foods with low GI scores have carbohydrates that take longer to digest. These foods will raise blood sugar levels slowly instead of spiking them. 

Typically, dietitians recommend people with blood sugar problems to eat foods with low GI scores. Here are GI ranges and some examples of foods: 

  • High – 70-100 – white rice, cornflakes, potatoes, watermelon, Special K, etc.
  • Moderate – 50-70 – beets, banana, ice cream, rye bread, etc.
  • Low – 0-50 – avocado, peanuts, broccoli, green beans, asparagus, mushrooms, etc.

It’s important to note that GI doesn’t take into account regular servings of foods, which makes it hard to apply in real life. For example, the GI of beets is 64. That’s for 50 grams of carbohydrates from beets, requiring you to eat about 12 cups of beets. I don’t know many people who can eat that many beets in one sitting! 

This is when Glycemic Load measurement offers a hand. 

Glycemic Load 

Glycemic Load (GL) considers the Glycemic Index AND the average serving size of foods. 

In case you are interested, GL is calculated by multiplying the GI of a food by the number of grams of carbohydrates in a typical serving of that food, divided by 100. 

Let’s use the beets example to illustrate it. Beets have a GI of 64 (fairly high), but in a typical serving of 1/2 cup, there will only be about 3 grams of carbohydrates. So, for a typical serving of beets, GL is less than 2, which is very low. 

Here are some examples of GL scores and ranges: 

  • High – 20 and above – potato chips, baked potato, rice, mac & cheese, etc.
  • Moderate – 11-19 – low-fat yogurt, banana, oatmeal, pizza, etc.
  • Low -10 or less – apple, carrots, watermelon, popcorn, etc.

By using foods with a low score on glycemic load AND paying attention to the serving size, you can significantly reduce your carbohydrate load per meal. As a result, you’ll make it much easier for your body to handle blood sugar rise. 

For instance, a typical American breakfast: 3⁄4 cup of Kellogg’s cereal (GL 16), a glass of skim milk (GL 9), and a glass of orange juice (GL 9) adds up to be a very high glycemic meal, total GL 34. Compare it with two eggs (GL 0), ½ avocado (GL 1), and two slices of cheese (GL 0), a total of GL 1.

Serious limitations of GI and GL

Even when we combine the Glycemic Index and Glycemic Load, the approach has significant problems.

  • First, GI and GL don’t account for other foods that you eat in a meal. It is important because the protein and fat in your meal will affect how quickly or slowly it will take you to digest and absorb it. As a result, the GI and GL will change. 
  • Second, there is a substantial individual variability in the GI of an ingredient. GI is calculated as an average response of 10 healthy people. Each individual’s response to food can vary significantly, even within a healthy population. Your blood sugar can go five times higher than mine when you eat a bowl of ice cream, but my response to a bowl of pasta might be five times higher than yours. 
  • Lastly, GI and GL can also be affected by the cooking methods, cooling time, food order in a meal, etc.

In conclusion

As you probably appreciate now, applying the Glycemic Index and Glycemic Load to your real-world situation can get complicated and inaccurate. If you don’t want to deal with charts of foods and their GI and GL numbers, here is my article on how you can significantly reduce the glycemic load of your diet in a much easier way.