The glycemic index is a reference chart that ranks foods and beverages on their potential to raise your blood sugar levels. Foods that rank below 55 are considered "low glycemic index" foods. These foods do not have as significant an effect on your blood glucose and insulin levels as higher-ranked foods. Low glycemic index foods and beverages are preferable for diabetics and dieters who want to keep their blood sugar as stable as possible.
Glycemic Index Rankings
Sandra Woodruff, a registered and licensed dietitian at Florida University University, explains what determines the glycemic index ranking of a food. Some people believe that "how much sugar" a food or drink contains is the primary factor determining its glycemic index. This is not so. The glycemic index of a food is influenced by a variety of factors. One factor is how processed the food is. Low glycemic foods undergo minimal or no processing, while high glycemic foods undergo high amounts of processing. Another factor is the type of carbohydrates the food contains. Low glycemic foods have natural sugar and no added sweeteners. Low glycemic foods also tend to have a lot of fiber as part of their carbohydrate content.
Low-Glycemic Foods
As a general rule, low-glycemic foods tend to contain complex carbohydrates rather than simple carbohydrates. Vegetables, which are among the very lowest foods on the glycemic index, also have the lowest calorie content. That is why the Centers of Disease Control and Prevention recommends using vegetables to manage your weight. Broccoli, cauliflower, celery, cucumber, eggplant, kale, spinach and all types of peppers are low-glycemic foods. Although fruits have sugar, they are among the lowest-ranking glycemic foods as well. Apples, oranges, blueberries, cherries, bananas, grapes and grapefruit are low-glycemic foods that rank under 55. All types of beans -- baked, black, pinto, kidney, navy and soybeans -- are low-glycemic foods. Noncarbohydrate foods such as fish, chicken, eggs and meat also have very low glycemic rankings or no ranking at all.
Benefits of Eating Low-Glycemic-Index Foods
Dietitian Sandra Woodruff reports several benefits of following a low glycemic diet and avoiding high-glycemic carbohydrate foods. Diabetics can keep their blood sugar stable by eaten low-glycemic foods. A low-glycemic diet may lower your risk of getting diabetes in the first place; men and women who eat a high-glycemic diet with low amounts of fiber are twice as likely to develop type-2 diabetes. A low-glycemic diet may also prevent certain cancers by lowering overall insulin levels. Eating a low-glycemic diet may also lower your risk of getting heart disease by reducing high serum triglycerides and raising low levels of HDL cholesterol. High-glycemic diets are associated with obesity and an inability to manage your body weight.
Glycemic Load
In his book "The 150 Healthiest Foods on Earth," Jonny Bowden, Ph.D. writes that a food's glycemic load, rather than its glycemic index, is a more accurate measurement to predict your body's after-meal glucose response. While Dr. Bowden acknowledges the glycemic index as a useful tool, he explains that it does not account for how much carbohydrate a food has per serving, which is a significant factor in raising your blood sugar. The glycemic load accounts for both the glycemic index and the amount of carbohydrates a food contains. Most food that has a low glycemic index also has a low glycemic load. Some foods, such as watermelon, have a high glycemic index but a low glycemic load, because they contain little carbohydrate per serving.
References
- "The 150 Healthiest Foods on Earth"; Dr. Jonny Bowden; 2007
- South Beach Diet Plan: Glycemic Index Food Chart
- Harvard Medical School: Glycemic Index and Glycemic Load for 100+ Foods
- Florida State University: Glycemic Index; Sandra Woodruff, MS
- CDC: How to Use Fruits and Vegetables to Manage Your Weight
- Joslin Diabetes Center: Insulin Action
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