UNDERSTANDING GLYCEMIC INDEX AND GLYCEMIC LOAD

Glycemic Index

The glycemic index (or GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar (glucose) levels after eating or in other words glycemic index of glucose is 100 and other foods are compared to glucose. Lower GI foods produce a slower and sustained release of blood sugar with a slower release of insulin. High GI foods breakdown faster during digestion wherein the blood sugar level increases rapidly with high insulin release.  

Having Low GI foods can result in the following benefits:

  1. Reduction in the fluctuation of blood sugar levels.
  2. Reduction in the risk of Type 2 diabetes, heart disease.
  3. Reduction in hunger and over-eating and thus trigger weight loss.

Classification

Glycemic Index

High GI

>70

Medium GI

56-69

Low GI

<55

 

Glycemic Load

The glycemic load (GL) considers the planned portion size of food as well as the glycemic index of that food, in other words, it is a better way to predict blood glucose values of different food types and amount size.

Glycemic Load = GI/100 multiplied by the net grams of planned carbohydrate (net carbohydrate is the total grams of carbohydrate minus the dietary fiber).

The implication here is a large amount of a low GI food may increase your blood sugar as much as a small amount of a high GI food.

For example:

Apple has a GI of 40  and contains 15g of carbohydrates

Glycemic Load (GL) of Apple = 40 X 15/100 = 6

A baked potato has a GI of 76 and contains 15 g of carbohydrates

Glycemic Load (GL) of Baked Potato = 76x15/100 = 11.4

 

Classification

Glycemic Load

High GL

>20

Medium GL

11-19

Low GL

<10

 

Implications of Glycemic Index (GI) for athletes

Understanding the Glycemic Index of food can help athletes in selecting the right type of carbohydrate. For a pre-exercise meal, a Low GI meal helps in controlling blood glucose concentrations during exercise. When the exercise is prolonged, reduced muscle glycogen utilization results in better endurance performance. Eating high GI meals before meals may result in a high increase in blood glucose levels and then a sudden drop in glucose levels within the 30 minutes of the exercise.