Glycemic Load vs Glycemic Index
Knowing the glycemic index/load of different foods is useful for many things. It can be used to enhance weight loss, regulate blood sugar levels, and optimize training.
What is Glycemic Index?
Glycemic index (GI) is used to measure how quickly carbohydrates from food enter your bloodstream and raise your blood sugar. It does this by assigning food a numeric score from 0 to 100, with pure glucose (sugar) having a value of 100. A food with a high GI contains carbohydrates that are easily digested, absorbed, and metabolized, resulting in a large spike in blood sugar. Food with a low GI is absorbed more slowly and will not have much of an impact on blood sugar. Generally, a food with a GI below 55 is low, 56–69 is moderate, and above 70 is high.
Challenges with Using Glycemic Index
The primary issue with using glycemic index is that it does not account for other factors, such as the effect of a mixed diet and the portion size that you would actually eat. The GI of a food is determined by giving a person 50 grams of carbohydrate of that food and seeing how it effects their blood glucose levels. However, this doesn’t give you the full picture because you can’t tell how much your blood sugar will actually increase when you eat the food as part of a normal meal. To get the full picture, you need to know how quickly the glucose will enter your bloodstream and how much carbohydrate is delivered per serving. Typically, when you have a meal, it is not comprised of a single food, but is a mix of carbs, fat, protein and provides other components that slow the absorption of glucose, such as fiber which modifies the glycemic impact. Portion size also plays a large role.
Why Use Glycemic Load?
Glycemic load (GL) provides a more fair and accurate method for ranking foods because it takes portion size into account. Like GI, it measures the effect of a food’s carbohydrate content on blood sugar but takes it a step further by accounting for the amount of carbs contained in a normal serving size of that food. Glycemic index uses an arbitrary base amount of 50 grams for every food, which doesn’t seem practical in a literal sense. You don’t eat 50 grams of every food. An interesting example of this is that to obtain 50 grams of carbs you could either eat 3.8 ounces of a donut or 25 ounces of watermelon. Seems silly, doesn’t it?
How to Calculate Glycemic Load
Glycemic load can be calculated by multiplying the quality of carbohydrate in a food (GI) by the amount of carbohydrate in a serving of that food and dividing that by 100. A food with a GL less than 10 is considered low, 11–19 is moderate, and above 20 is high.
GLfood = (GIfood x amount of available carbohydrate per serving in grams) /100
For example, watermelon has a GI of 76, which is as high as a donut. However, the watermelon provides 11 g of available carbohydrate per serving while a donut provides 23 g. Using the formula above:
GL watermelon = (76 x 11) /100 ~ 8
GL donut = (76 x 23) /100 ~ 17
Understanding glycemic load/index allows you to help regulate blood sugar, increase energy in training, and aid in weight loss. If you would like help, contact us and we’ll set you up with a nutrition plan that is tailored to meet your goals!