Low-glycemic index diet: What’s behind the claims?

By | May 4, 2023

The presence of fat or soluble dietary fiber can slow the gastric emptying rate, thus lowering the GI. In general, coarse, grainy breads with higher amounts of fiber have a lower GI value than white breads. The GI value of a food does not take real-life application into consideration.

In addition to the cooking method used, the degree of ripeness may also affect the GI of some fruits, including bananas. This is because the amount of resistant starch decreases during the ripening process, leading to a higher GI . Glycemic load is calculated by multiplying the GI value by the number of carbohydrates per serving, then dividing that number by 100.

A GI value tells you nothing about other nutritional information. For example, cantaloupe has a medium to high GI score and a medium GL score. But it is a good source of vitamin C, beta carotene and other important nutrients.

The glycemic index shouldn’t be the only thing you consider when making choices about what to eat. The fact a food has a low glycemic index doesn’t mean it’s super-healthy, or that you should eat a lot of it. Foods that are close to how they’re found in nature tend to have a lower glycemic index than refined and processed foods. The smaller the number, the less impact the food has on your blood sugar.

Enter search terms to find related medical topics, multimedia and more. For example, he says one study of instant oatmeal showed that it had a glycemic index of 79, which is the high range. Yet steel-cut rolled oats have a glycemic index of 55, which puts it in a medium glycemic index.

Individual responses may vary based on other factors including other foods eaten in combination with the carbohydrate. To help you understand how the foods you are eating might impact your blood glucose level, here is an abbreviated chart of the glycemic index for more than 60 common foods. A more complete glycemic index chart can be found in the link below. Firstly, the GI scale does not consider the nutritional value of foods. Foods that are high GI are not necessarily unhealthy, and not all low GI foods are healthy.


  • “The Glycemic Index: Methodology and Clinical Implications” by David J. Jenkins et al. (1981)
  • “International Tables of Glycemic Index and Glycemic Load Values: 2008” by Kaye Foster-Powell et al. (2008)
  • “The Glycemic Index: Physiological Mechanisms Relating to Obesity, Diabetes, and Cardiovascular Disease” by Jennie C. Brand-Miller et al. (2002)
  • “Glycemic Index, Glycemic Load, and Risk of Type 2 Diabetes” by Frank B. Hu et al. (2001)
  • “Dietary Glycemic Index and Glycemic Load and the Risk of Type 2 Diabetes in Older Adults” by Rob M. van Dam et al. (2010)


  • David J. Jenkins, a Canadian professor of nutrition and metabolism who developed the glycemic index in the early 1980s
  • Jennie C. Brand-Miller, an Australian professor of human nutrition who has extensively researched the glycemic index and its health implications
  • Frank B. Hu, an American epidemiologist and nutritionist who has researched the relationship between the glycemic index and type 2 diabetes
  • Kaye Foster-Powell, an Australian dietitian who has contributed to the development of international tables of glycemic index and glycemic load values


  • University of Toronto Department of Nutritional Sciences, where David J. Jenkins developed the glycemic index
  • University of Sydney’s Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders, where Jennie C. Brand-Miller works
  • Harvard T.H. Chan School of Public Health, where Frank B. Hu is a professor of nutrition and epidemiology
  • University of Sydney’s School of Molecular Bioscience, where Kaye Foster-Powell works