High GI carbs? Low GI carbs? Is the Glycaemic Index even worth using?

Most of us will have been told that we should be eating more “low GI” carbs and eating less “high GI” carbs. But is this really the case?  Does GI matter?


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The Glycaemic Index

First off, let me give a quick rundown of what the Glycaemic Index (GI) is.  It is a system that was developed back in the 1980s.  It was created as a way to rate by how much different sources of carbohydrates raised blood sugar levels.  Each food was given a score out of 100.  High GI foods having a greater effect on raising blood sugar, and low GI foods having less of an effect on blood sugar.  Since we ideally want to keep our blood sugar levels stable, it seems that the advice of favouring low GI foods over high GI foods makes sense.



The problem

Here’s the thing.  When the Glycaemic Index was put together, each carbohydrate source was tested when consumed in isolation.  On the surface, this doesn’t sound like an issue.  However, this does not reflect how the majority of us will consume our carbohydrates.  We eat our food in meals, that include a mixture of carbs, protein, fats, plus fibre.  All of these have an effect on slowing the rate of digestion.  This also limits any potential blood sugar spike.  Rarely would we ever eat a source of carbohydrates in isolation – which is how they were tested when putting together the Glycaemic Index.


Therefore, the Glycaemic Index is unrealistic.  You could argue that white rice should be avoided, as it is high GI and it will spike blood sugar levels.  However, eat that white rice with steak and broccoli, and no longer will it spike blood sugar.

You could argue that bread should also be avoided, as it is high GI and will spike blood sugar.  But use that bread to make a turkey sandwich, and again any blood sugar spikes won’t be an issue.


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Best Sources of Carbs on a white wooden background. Top view

Another problem

To point out further how flawed the Glycaemic Index, is it turns out that every individual’s blood sugar levels react differently.  People have different levels of sensitivity to carbohydrates.  So while a carbohydrate source might spike one person’s blood sugar, it may have minimal effect on another person!




The Glycaemic Index isn’t a particularly reliable way to judge how “healthy” a food source is. For example, a chocolate bar is actually a “low GI” food due to its fat content.  Despite chocolate having a high sugar content!

But really, as long as you are aiming for the majority of your food to come from natural, minimally refined, minimally processed, whole foods, then your diet should be just fine!

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