Glycemic Index List – Why it Needs to Be Taken With a Grain of Salt

Keeping tabs on the quality of your food is no small task these days: we are surrounded by food choices that make so many of us overweight and unhealthy. Today, many scientists believe that the glycemic index list is the best tool we have to recognize which foods will help us lose weight and get healthier. But you may be surprised to know that the numbers do not tell the whole story. To really succeed on this diet, you need to go beyond them. Here is why.

Glycemic index was designed to tell us which foods raise blood sugar levels by how much. Originally used by people suffering from diabetes and their doctors, this indicator is now widely recognized and used as a tool for both losing weight and improving health. GI values have been calculated for a number of commonly used foods and an extensive list is available in medical literature. Pure glucose is given a Glycemic index of 100 and the Glycemic index list consisting of various foods is composed relative to this value.

In order to create a Glycemic index list, the scientists had to test various foods on people and see how they raise the blood glucose level compared to pure glucose. However, this process is a case of easier said than done. The results depend on a number of parameters: this actually makes the values oscillate. Here are some of the reasons why GI numbers (and your results!) may vary and can even mislead you:

Food combinations will have an impact of how foods affect your blood sugar. Proteins will slow down the absorption, leading to some surprising results. For instance, a Snickers bar has a GI value lower that that of a plain bagel. Is it better for you? You decide.
Differences between foods: No two nuts or fruits or other foods are alike in nature and they invariably contain slightly different levels of carbohydrates in them.
Differences between people: Different people have different body metabolism, which means the rise in glucose level is different.
Differences between recipes: For prepared foods, different research groups might use different recipes, which affect the blood glucose level rise.
Differences between laboratory techniques: Testing techniques are not universal in nature and thus different research groups adopt slightly different techniques. This invariably causes a difference in the final result.
The numbers the index uses are only a qualitative analysis of foods: they do not take the quantity of food consumed into consideration.

For all these reasons, the Glycemic index list generally contains a range of values for each type of food. However, many lists simply take the average value of all the tests conducted with that food on various individuals.

Bottom line: if you intend to base your diet on GI numbers, it is worth remembering that (1) the Glycemic index list only provides approximate average values instead of sharp values and (2) there is no substitute for common sense. These lists provide for a good comparison of foods, and therefore aid you in the selection of your diet, if and only if you know how to use them.