Who Needs Carbs

managing an LCHF lifestyle in Israel

Glycemic index

(March 13, 2012)

It’s very popular today to talk about the “glycemic index” (GI) as a measure of quality and “healthfulness” of a particular food. But is it really a good measure?

The concept was developed in the early 80’s in Canada by Dr. David J. Jenkins and his colleagues. They looked for a way to check what food is better for diabetics and saw that different food raises blood sugar levels differently – some peaked high and fast, and some raised less and slower. They tested and prepared tables. To compare they took 100 g glucose and determined that as GI = 100. Thus they got (decided) that GI below 55 is considered low, GI of 56-69 is medium, and GI of 70 and up is high.

But – There are some problems … For example:

  1. The GI doesn’t say anything about the amount of insulin required to break down the sugar in the blood. The amount of insulin depends on the amount of carbohydrates so eating a small amount of something with a high GI may be the same as or even better than eating a large amount of something with a low GI. The insulin amount needed is also depending on the level of insulin sensitivity (whether it’s a healthy or diabetic person).
  2. There are foods that everyone can agree on as not being the most vital to our health and they have a low GI, such as a simple sponge cake (GI = 46) or peanut M&Ms (GI = 33).
  3. The GI is only an average number and the actual value can vary depending on ripeness, storage, processing, variety, etc. Furthermore, there are two values of GI for everything as there are two types of tables – One compares with 100 g glucose and the other compares with 100 g of white bread (which then gets the 100 base point). So when one’s comparing foods one should make sure they are from the same table …

A better and more accurate way to measure is the “glycemic load” (GL) that also takes into account the amount you eat. Thus you can see that for watermelon with a high GI (72), the GL is only about 4. On the other hand, the sponge cake mentioned before has a GL of 17. (Below 10 is considered low, 11-19 is medium and 20 and up is considered high.)

And a small curiousity (and a question, of course 😉 ) – For spaghetti made of white flour the GI = 38, whole wheat flour spaghetti the GI = 37. Their GL is 18 and 16. In short there’s not that big difference, right? So why is one more recommended for diabetics than the other?

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This entry was posted on March 24, 2012 by in General and tagged , , , , , , , , .

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