Why The Glycemic Load Is Important

Carbohydrates, Blood Sugar, and Insulin

Is there a difference between the glycemic index and the glycemic load? Both are indicators of a food’s impact on blood glucose and insulin levels. More specifically the glycemic index and load measure the food’s carbohydrate effect on blood sugar. High blood sugar is harmful to our health in many ways. Insulin is the main fattening hormone. Higher insulin levels lead to fat gain. The glycemic index and glycemic load are useful tools to help you determine which foods you can eat to keep blood sugar and insulin levels at healthy levels.

Glycemic Index and Glycemic Load

The glycemic index is determined by measuring the impact of 50 grams of a carbohydrate on blood sugar and comparing it to the effect of 50 grams of glucose on blood sugar. The glycemic index of glucose is set at 100. If the carbohydrate tested has one-half the impact on blood glucose as glucose then it’s glycemic index is 50. If it is five percent higher than its glycemic index is 105.

So the glycemic index compares the effects on blood sugar from the consumption of an equal number of grams of carbohydrates. The shortcoming of the glycemic index is that the carbohydrate content in the typical serving of food varies significantly. That’s where the glycemic load is helpful. It takes the glycemic index and corrects it for the carbohydrate content per serving. The glycemic load provides a more complete picture of the effect of a particular food on blood sugar.

The glycemic load is calculated by taking the glycemic index and multiplying it by the number of grams in a serving of a given carbohydrate and then dividing that by 100. So food with a glycemic index of 50 that contains 5 grams of carbohydrates in a serving has a glycemic load of 2.5. Calculated (50 x 5)/100.

Generally, the glycemic index and glycemic load closely approximate the effects of a carbohydrate on blood sugar, but there are cases where they diverge. Watermelon is the classic example. Watermelon has a glycemic index of 72 which is considered high (glycemic index above 55 is considered high). But, since watermelon is mostly water it only contains 5 grams of carbohydrate in the typical serving giving watermelon a glycemic load of 3.6 which is considered low.

Glycemic Load: What’s Good?

Avoid foods with glycemic loads 20 or higher. If you need to lose weight, have DM, abnormal cholesterol, or elevated BP focus on foods with glycemic loads of ten or less.

• Glycemic load > 20:  is high and unhealthy.
• Glycemic load 11 – 19:  is moderate (unhealthy if trying to lose weight or have metabolic syndrome, acceptable if weight is controlled).
• Glycemic load < 10:  is low and healthy.

This link provides the glycemic load of some of the more common foods.

Updated May 27, 2022.