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Low glycemic index diet


Also listed as: Diet, low glycemic index, Glycemic index diet
Related terms
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Glycemic index

Related Terms
  • Carbohydrates, David Jenkins, diet, GI, GI diet, Glucose Revolution, glycemic index, insulin, low-GI, low glycemic index, Rick Gallop, Sugar Busters.

  • The glycemic index is a numerical index that ranks carbohydrates based on their rate of glycemic response (i.e. their conversion to glucose within the human body). Glycemic index uses a scale of 0 to 100, with higher values given to foods that cause the most rapid rise in blood sugar. Pure glucose serves as a reference point and is given a glycemic index (GI) of 100.
  • Foods with a high GI are those that are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels. Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels and have proven benefits for health.
  • Glycemic index values are determined experimentally by feeding human test subjects a fixed portion of the food (after an overnight fast) and subsequently extracting and measuring samples of their blood at specific intervals of time. The earliest known work on the glycemic index was done by Dr. David Jenkins and associates at St. Michael's Hospital in Toronto, Canada. The diet increased in popularity when Rick Gallop published "The G.I. Diet: The Easy, Healthy Way to Permanent Weight Loss" in 2001.

Theory / Evidence
  • Foods that cause a large and rapid glycemic response or that have a high glycemic index will elevate energy and mood at the initial phase, but will also release an excess amount of insulin and drive blood sugar back down too low. Therefore, these foods may lead to a cycle of increased fat storage, lethargy, and even more hunger.
  • The theory behind the glycemic index is to minimize insulin-related problems by identifying and avoiding foods that have the greatest effect on blood sugar, especially for those with diabetes.
  • Low GI diets have been shown to improve both glucose and lipid levels in people with diabetes (type 1 and type 2) and reduce insulin levels and insulin resistance. Low GI diets may also have benefits for weight control because they help control appetite and delay hunger.
  • There are several limitations of this diet. There is a scarcity of GI data, with only five percentof the foods having GI values. There is a wide variation in GI measurements; for example, baked Russet potatoes have been tested with a GI as low as 56 and as high as 111. GI values can be affected by preparation method and by combination with other foods. There may be individual differences in glycemic response.
  • Reliance on GI may lead to over consumption. GI should be used only for a rating of a food's carbohydrate content. If it is used as the sole factor for determining diet, individuals may easily end up over consuming fat and total calories.
  • A major criticism of the GI diet is that the reference food used to determine the glycemic index, white bread, is popular only within a particular culture. Even proponents of this diet acknowledge that the glycemic index tests were developed for people who eat at least 50 grams of carbohydrates per day. Results for people whose foods do not feature large amounts of carbohydrates have not been investigated.


Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Acheson KJ. Carbohydrate and weight control: where do we stand? Curr Opin Clin Nutr Metab Care. 2004 Jul;7(4):485-92.
  2. Gallop, Rick. The G.I. Diet : The Easy, Healthy Way to Permanent Weight Loss. New York: Workman Publishing Company. 2002.
  3. GI Database.
  4. Glycemic Index, Glycemic Load, Satiety, and the Fullness FactorT.
  5. Home of the Glycemic Index.
  6. Mendosa, D. The Glycemic Indices.
  7. Wylie-Rosett J, Segal-Isaacson CJ, Segal-Isaacson A. Carbohydrates and increases in obesity: does the type of carbohydrate make a difference? Obes Res. 2004 Nov;12 Suppl 2:124S-9S.

Glycemic index
  • Foods are rated as having a low, intermediate, or high Glycemic Index. Advocates claim that people should avoid foods with high glycemic indices as much as possible.
  • A glycemic index of 55 or below is considered low and 70 or above is considered high.

Copyright © 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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