Glycemic Index

What is the glycemic index?

The glycemic index (GI) ranks foods according to how they affect blood sugar levels. The index specifically targets carbohydrates and ranks them on a scale from 0 to 100. Foods with a high GI are more quickly digested and absorbed resulting in a greater rise in blood sugar levels. Foods with a lower GI are more slowly digested and absorbed and cause blood sugar to rise more gradually.

Generally speaking, processed foods have a higher GI rank than foods that are unprocessed. For example, white bread, pasta and baked goods have a higher glycemic ranking than dried beans, non-starchy vegetables and most fruits. Meats and fats are not included in the glycemic index because they do not contain carbohydrates.

Ranking foods

When planning meals using the glycemic index, the overall goal is to choose foods that have a low to medium ranking. You can use the following as a guide:

• Low glycemic foods have a ranking of 55 or less
• Medium glycemic foods have a ranking of 56 to 69
• High glycemic foods have a ranking of 70 or higher

Here are examples of low, medium and high glycemic foods and their ranking:

Low – 55 or less

• Kidney beans - 24
• Chickpeas – 28
• Lentil beans – 32
• Apple – 36
• Orange – 43
• Banana - 51
• Sweet corn – 52

Medium – 56 to 69

• Potato chips - 56
• Potato (French fried) – 63
• Potato (sweet) – 63

• Popcorn – 65
• Brown rice – 68

High – 70 or higher

• White rice 73
• Whole wheat bread – 74
• White wheat bread – 75
• Watermelon - 76
• Potato (boiled) – 78
• Cornflakes – 81
• Potato (mashed) – 87
• Rice milk – 86

Factor in portion sizes

The glycemic index is widely recognized as a helpful tool for determining how foods will affect glucose levels. But it is also controversial in the treatment of diabetes. Using only the glycemic index to create a meal plan does not take portion size into account when factoring the ranking. To get a complete picture of how blood sugar will be affected by any food you eat, you must consider both the glycemic index and the amount you eat. A concept called the glycemic load attempts to bring these two elements together.

How does the glycemic index compare to the carb counting?

For most people, carb counting is the preferred method for managing blood glucose. It is a more precise way to predict how the intake of carbohydrates might affect blood sugar levels. The glycemic index can be used effectively as an add-on to help you finetune the food choices you make. The most important part of any meal plan is to ensure that it is customized for your personal health and lifestyle needs. A dietician can create a meal plan designed for your needs that includes tips on using the glycemic index.

_Sources:

Foster-Powell, K., Holt, S., Brand-Miller, J.C.

International table of glycemic index and glycemic load values: 2002. American Journal of Clinical Nutrition Vol. 76, No. 1, 5-56, 2002. http://www.ajcn.org/cgi/reprint/76/1/5.pdf

Glycemic Index and Diabetes. American Diabetes Association. Accessed June 2, 2009. http://www.diabetes.org/food-and-fitness/food/planning-meals/glycemic-index-and-diabetes.html

The Glycemic Index and Diabetes. Joslin Diabetes Center. Accessed June 2, 2009. http://www.joslin.org/managing_your_diabetes_698.asp

Mendosa, David. Revised International Table of Glycemic Index (GI) and Glycemic Load (GL) Values—2008. Accessed June 3, 2009. http://www.mendosa.com/gilists.htm