Glycemic Index (GI)
The glycemic index is a system of ranking foods on a scale of 0 to 100 according to how high blood glucose peaks within two hours of consuming the specific food. Foods assigned a high GI result in higher peaks in blood glucose compared to foods with lower GIs. However, portion sizes are based on 50 grams of carbohydrate, which is not always the amount of food a person typically consumes.
For example, 50 grams of carbohydrate from pasta is equal to slightly more than one cup cooked, which is a reasonable amount of pasta to eat in one sitting.
On the other hand, 50 grams of carbohydrate from baby carrots requires a 7 cup portion! For this reason, glycemic load may be a more practical use of the glycemic index concept.
Glycemic Load (GL)
The glycemic load is based on glycemic index but uses standard portion sizes rather than 100 grams of carbohydrate. The formula used for calculating glycemic load is:
GL = (GI x the amount of carbohydrate) divided by 100.
So, if an 8-ounce glass of skim milk, which contains 12 grams of carbohydrate, has a glycemic index of 46, the glycemic load is:
GL = 46 x 12 ÷ 100 = 5.52
Generally speaking, the ranking for glycemic load is as follows:
- Low = 10 or less
- Medium = 11-19
- High = 20 or more
Remember, the lower the glycemic load for a food, the lower the rise in blood glucose after it is eaten.
For more information on glycemic index and glycemic load including food rankings: glycemicindex.com
The complete list of the glycemic index and glycemic load for 2,480 foods can be found in the article "International tables of glycemic index and glycemic load values: 2008," by Fiona Atkinson, Kaye Foster-Powell, and Jennie Brand-Miller in the December 2008 issue of Diabetes Care, or at this site: