Glycemic Index Values of Meals

To determine the Glycemic Index values of meals, we need 2 pieces of information:

  • The amount of carbohydrates (grams) in the meal.
  • The percentage of available carbohydrates (meaning carbs that can be fully absorbed in the body) contributed by each food.


This may seem very complicated, but this information is normally available from the majority of nutrition tables … and once we have this, we can do the following calculation:

For each food item, multiply the Glycemic Index value by the percentage of the total carbohydrate. Add the totals, and we have the Glycemic Index values for any given meals.

Let’s take a look at an example…

  • Meal = 2 slices of toast (2oz) and a glass of milk (4oz).
  • There are approximately 26 grams of carbs in the toast and around 6g of carbs in the milk.
  • Sum of the carb content is 32g. (which means toast is 81% & milk is 19%)
  • Then the GI of bread is ~70; the GI of milk is ~28.

Calculation = Glycemic Index X Carbohydrate Percentages

Toast: 70 X 81% = 57
Milk:   28 X 19% = 5
Total: 57 + 5 = 62

So regarding Glycemic Index values … this meal is 62.


Eating non-standard foods

If we eat foods that do not have a GI score, or are prepared in a way that’s not been tested for glucose response yet (i.e. non-standard food), determining a true glycemic index value it not achievable. However, by using glycemic index charts and food composition tables we can get pretty close for most meals.

Glycemic Index Related Blogs