The Glycemic Index Diet

The eighth installment of the series on eating patterns is about the Glycemic-Index Diet. Last month, we explored the Volumetrics Diet and discussed how a food’s energy density can be used to help people make healthier choices when trying to lose or manage their weight. Ranked #23 out of 41 total diets in the U.S News Best Diet Rankings, the Glycemic-Index Diet is based on a carbohydrate’s effect on a person’s blood sugar. “Good” carbs rank lower in the index and take longer to digest, which slows the rise in blood sugar, while “bad” carbs rank higher in the index and tend to cause spikes in blood sugar.

Glycemic-Index Diet: In a nutshell, most carbohydrates (dairy, grains, fruits and vegetables) have been ranked from 0-100. The higher the number, the more of a blood sugar spike the food will cause when consumed. For example, the GI of white rice is 73, dates is 42 and soy beans is 16. The premise is that participants eat more of the lower-GI foods than the higher ones.

Nutritional Considerations: While consuming higher-quality carbohydrates is always a good idea, the Glycemic-Index Diet leaves a lot to be desired. First, the diet doesn’t address intakes of protein and fat sources, which are both important parts of each meal and snack and have an impact on any effect the carbohydrate being consumed with them has on blood sugar. Second, the GI Diet has not been proved to be effective at long-term weight loss and/or maintenance. Third, not all carbohydrates have a GI ranking (ex. processed foods, such as a boxed cracker) and details such as the ripeness of a piece of fruit or how a food is prepared can affect its effect on a person’s blood sugar. Lastly, labeling foods “good” and “bad” based on their effect on blood sugar is misguided, as it dismisses the food’s other nutritional benefits.

Target Audience: This diet may appeal most to those with Diabetes, for whom managing blood sugar is essential to a healthy lifestyle. It could be helpful for diabetics to have some knowledge of where the foods they eat most often fall on the index. However, because a food’s effect on blood sugar is impacted by what is eaten in conjunction with it, the food’s ranking on the GI is only part of the equation. The diet can help participants lose weight initially.

Foods to Highlight: Carbohydrates lower on the GI, such as muesli (57) instead of cornflakes (81) or an apple (46) instead of watermelon (76). Carbs that have more fiber, fat and/or protein than others will be lower on the scale. Foods high on the GI are not prohibited, simply recommended in smaller amounts than foods lower on the scale.

Holly R. Layer is a Registered Dietitian and a freelance writer.  She teaches fitness classes at the Southtowns YMCA and leads nutrition tours at the East Aurora Cooperative Market.  She lives in the village with her husband, Andrew, an East Aurora native. She blogs at Questions can be emailed to Holly at 


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