Glycemic Index v Glycemic Load

Most people these days have heard of the term Glycemic Index as it seems to be bandied about by all sorts of health 'professionals' and other so called experts. So what's the real deal with the Glycemic Index and perhaps more importantly, the Glycemic Load of a food?

First of all we need to understand that when any type of carbohydrates are digested, sugar in the form of glucose enters the bloodstream. The brain then tells the body to produce insulin which allows the sugar to get to the muscles where it is needed. Insulin also helps bring sugar out of the bloodstream by converting the excess sugar into fat and storing it in the body. The Glycemic Index, (GI) of a food is a measurement of the rate in which the sugar enters the bloodstream. The higher the GI, the faster the sugar enters the blood. The trouble with a higher GI is the pancreas releases more insulin than it would otherwise, this creates a drastic lowering of blood sugar levels which 'scares' the brain into thinking it is about to starve so therefore more of the sugar gets stored as fat - usually belly fat!

GI is scored on a scale from 0 - 100, but here's where it gets interesting; carrots have a GI of 40 - 45! So does that mean eating carrots will make us fat? No, of course not because although the sugar from a carrot enters the bloodstream very quickly, there is very little sugar in carrots in the first place. And this is where the Glycemic Load, (GL) comes in; the GL of a food takes into account not only the speed of which the sugar enters the bloodstream, but also the amount of sugar in the food in the first place. So although our friendly carrot has a high GI, it has a low GL due to the low sugar content.

So be very aware when you read about certain foods having a low of high GI; check the GL first - advertisers are very clever about sharing just the information they want you to know. And just so you know, glycemic load is also a case of the the lower the better. To work out the glycemic load of a food, you need to multiply the GI by the amount of grams of carbohydrates and divide by 100. Here's a great explanation of how to work out the GL of your food. 


  1. Great post, Chris! It's true, all of these scales need to be taken with a grain of salt. But definitely in general low glycemic foods put less strain on the body, and I feel better on a generally low-GI diet. But the only high-GI foods I actually cut out are the processed junk foods - I keep carrots in quite happily, thanks!

  2. Thanks Anna, I think it's important for people to know about GL and not just GI. Then they can make more informed choices

  3. Out of curiosity, do you know what the Glycemic Load of carrots would be then?

    1. Good question Shelly, I've amended the post to explain exactly that with a really god link to understand the workings better.

    2. Shelly,
      You can find the GI and glycemic load of several thousand common foods here: .


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