Diet and Carbohydrates: What Is Glycemic Index?

Diane Wade, MS, RD, CNSC, from Sharp Grossmont's Clinical Nutrition Department, offers information about assessing tools for managing your carbohydrate intake.

Carbohydrate foods come in many forms, and all are not created equal. In fact, our bodies respond differently to various types of carbohydrates. Glycemic index — commonly known as GI — is a rating system for measuring the impact of carbohydrates on a person’s blood-sugar levels. Low GI carbs have less of an effect on blood glucose and insulin levels, which help reduce risk of heart disease and diabetes.

GI was first developed in 1981 by Dr. David J. Jenkins of the University of Toronto as a way to improve upon carbohydrate exchange lists used by diabetics. Dr. Jenkins’s research pointed out that all carbohydrate foods are not the same and neither are the body’s glucose and insulin responses to those foods. 

GI compares the effects of carbohydrates to that of 50 grams of white bread, which has a GI level of 100. An index lower than 55 is considered low range, 55 to 70 is moderate and foods greater than an index of 70 is considered high. Since meats are not carbohydrates, foods such as beef, pork, chicken, fish, etc., do not have a GI rating.

While GI levels represent the type of carbohydrate in foods, standards may vary based on the amount of carbohydrate consumed. Keep the following in mind when incorporating GI into your meal plan:

  • GI of a food may differ when eaten alone versus combined with other foods
  • Many nutritious foods may have a higher GI than foods with little nutritional value, and the use of GI should be balanced with basic nutrition principles that enlist a variety of healthful foods and moderation of foods with low nutritional value
  • Portion control is the overall key in managing blood glucose levels or losing or maintaining weight

Based on research, carbohydrate counting should be the first tool for managing blood glucose levels, particularly for diabetics. Research shows that both the amount and the type of carbohydrate in food affect blood glucose levels. Studies also show that the total amount of carbohydrate in food, in general, is a stronger predictor of blood glucose response than the GI. More information can be found on the American Diabetes Association’s website.

Paying attention to what you eat and how much you eat can help avoid a multitude of health ailments. Educate yourself as much as you can about the calories and nutrients in the foods you eat. Take advantage of whatever tools are out there, including glycemic index, to help you make informed choices.

We hope you find the above website helpful, but please remember that Sharp HealthCare does not control or endorse the information presented on this website, nor does this site endorse the information found on www.sharp.com.

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To learn more about Sharp's nutrition services or to find a Sharp-affiliated physician, search for San Diego doctors or call 1-800-82-SHARP (1-800-827-4277), Monday through Friday, 8 am to 6 pm. To find general information about nutrition, read the Nutrition News archive.