Glycemic Index (GI)


Original Image by Bobbi Bowers via Flickr
Original Image by Bobbi Bowers via Flickr

By: Nikki Nies

The Glycemic Index (GI) is a tool used to indicate how foods impact glucose levels and insulin.  The lower the glycemic index number, the less the food impacts blood sugar levels.  With foods numbered from 1 to 100, the closer the number is to 100, the higher the glycemic index and the more it impacts blood sugar levels. When meal planning, it’s ideal to choose foods that have been labeled low or moderate on the glycemic index.  gi_graph

Low glycemic foods, listed as 55 or less includes dried beans, legumes, non starchy vegetables, whole grains and most cereals.  Moderate glycemic foods are between 56-69 and include quick oats; whole wheat, rye and pita bread; couscous; brown, white or basmati rice.  High glycemic foods are between 70-100 on index and include white bread or bagels; russet potato, pumpkin; melons and pineapple; rice pasta; macaroni and cheese; corn flakes; instant oatmeal; bran flakes; puffed rice; pretzels; rice cakes; popcorn and saltine crackers.

Factors that influence GI:

  • Fiber and fat content positively influence GI.
  • Storage time and ripeness: the riper the fruit, the higher the GI
  • Cooking method: al dente pasta has a lower GI than soft cooked
  • Variety: converted long grain rice has a lower GI than brown rice, but shorter grain white rice has a higher GI than brown rice
  • Processing: juice has a higher GI than whole fruit; mashed potato has a higher GI than a whole baked potato; stone ground whole wheat bread has a lower GI than whole wheat bread

Often  times, the more processed and cooked a food is, the higher the GI.  Yet, there are some exceptions.

To determine the GI rating, measured portions of the food containing 10-15 g of carbohydrates given to 10 healthy people.  Foods are compared to how they raise blood glucose levels in comparison to a reference food, such as white bread or or glucose.  Meats and fats are not included in the glycemic index as they do not contain carbohydrates.  

Like any tool, the glycemic index should be used in relation with other blood glucose monitoring tools.  There are some limitations to the tool as not all indices are accurate.  For example, while bananas are ranked as having a moderately high glycemic index, they are not denoted as “bad.”  Also, GI doesn’t take into account the amount of carbohydrates consumed.  One needs to take into consideration portion control in regards to diabetes and weight management.

Check out the full list of foods and where they rank on the glycemic index for a better idea of the overall impact on one’s body.

Photo Credit: Gena Livings 

Sources: http://www.glycemicindex.com/about.php

http://shine.yahoo.com/healthy-living/7-health-food-myths-mom-got-wrong-3-154100607.html

http://www.whfoods.com/genpage.php?tname=faq&dbid=32

http://www.diabetes.org/food-and-fitness/food/what-can-i-eat/understanding-carbohydrates/glycemic-index-and-diabetes.html

http://www.health.harvard.edu/newsweek/Glycemic_index_and_glycemic_load_for_100_foods.htm

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