GI Scale…Fail!

The glycemic index (GI) was released a number of years ago to help us make educated decisions on what foods have the biggest impact on our blood sugars. Which, in theory is great… If we can avoid the huge fluctuations in blood sugars, our energy levels are far more consistent throughout the day, our risk of degenerative disease decreases and we are far less likely to store the extra energy as body fat. The scale works like this. Anything below 25 is low, 25 to 50 is medium and over 50 is a high sugar hit. But this also depends on who you talk to.

However, like many things from the so called “experts”, the glycemic index is completely flawed and misleading. The first issue with it is that when you create a scale of this kind, you need something to compare it to. The most common comparison used is glucose. Glucose being pure sugar and the highest glycemic food is given a figure of 100. But then some other genius comes along and says that is not good enough and white bread should be used as the 100 mark of the scale. In my opinion, there should be one standard across the board as two just causes too much confusion. And confusion is just, well, confusing!

Now this issue is just a minor one, you just need to be sure which scale you are reading. Not too hard at all really. The main issue with it is this. The index is based on how 50 grams of carbohydrate/sugar affects your blood sugar. Now I’m not sure if everyone realises this, but not all foods contain 50 grams of carbohydrate. Some have more, some have less. This is the most misleading thing. 

To counteract this huge flaw, there is a lesser known scale called the Glycemic Load (GL). Basically, the best way to describe the two scales together is to use the analogy of a car crashing into a brick wall. A bit morbid, but it works. The GL scale can best be looked at as the size of the car, a mini at the bottom of the scale and a truck at the top end of the scale. The GI scale can be looked at as the speed the car is travelling before it hits the wall. You can have both vehicles hit the wall at the same speed, same GI, but the truck, higher GL, will do far more damage. so looking at the GI scale by itself, can be very misleading.

The GL scale is measured with anything below 6 being low, 6 – 12 is medium and over 12 is high.

Let’s look at it in the real world with food. The best examples I have found is with carrots and spaghetti. Keep in mind, these figures can vary, but the ones tested measured as follows.

The carrot has a GI of 49 (Peeled and boiled, Sydney Australia) and the pasta has a GI of 50 (white spaghetti boiled 180 grams, made in Canada). At first look, they are quite similar. But when you look at the GL scale, 80 grams of carrots are a tiny 2, and 180 grams of pasta is 24. Remember, 12 is considered high and the pasta is 24! So looking at just the GI scale, they are almost the same, but you would have to eat about a kilogram of the carrots to get close to the sugar hit of 180 grams of pasta. Not something I would be willing to do in one go.

So you can make the best choices of food, I have included a link to a PDF of the glycemic index and load. It is a huge document but each food is listed in different groups for easy reference so it is quite easy to find what you are after. They reference both the glucose scale and the white bread scale, so just make sure to check which one you are reading.

Till next time

Run Well

Chris O’Driscoll

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