What’s the big deal with the Glycemic Index?! A lot actually. Call me a nerd if you like, but the Glycemic Index really gets me tickin’.
The Health Junction has a super smart science friend named Janice, aka, Jawesome who runs Canada’s leading laboratory in the area of clinical nutritional research. I was lucky enough to visit Jawseome at work yesterday and spent three hours watching the ins and outs of Glycemic Index Labs. GI Labs was founded by Dr. Thomas Wolever (check out his latest book here) who along with David Jenkins came up with the revolutionary concept of Glycemic Index for carbohydrate selection in their now famous 1981 study published in the American Journal of Clinical Nutrition.
I’m proud to say that these two pioneers of nutritional sciences continue to teach at the University of Toronto’s Faculty of Medicine (Nutritional Sciences) but interestingly, Canada is the only place in the world where Glycemic Index ratings cannot be displayed on food packaging. My friend Janice, did her thesis at U of T on GI methodology under the supervision of Dr. Wolever (who I met yesterday!!) and offered some great insight into why the GI is a great tool to understand for us everyday lay people.
Simply put, the GI works by measuring how a food changes blood sugar levels. Low GI foods cause a slow, gradual rise and then a subsequent gentle fall in blood glucose. High GI foods will result in a sudden spike and quick fall in blood glucose levels. Foods are ranked out of 100; low GI is 55 or less, high GI is 70 or more.
Why are lower GI foods ideal?
Eating carbohydrates that have a high GI results in rapid fluctuations in blood sugar and over time can result in problems with blood sugar control – commonly expressed as hypoglycemia. Over time, insulin, which helps shuttle glucose into the cells for energy, becomes less effective and ultimately can lead to Pre-Diabetes or Type II Diabetes. Diabetes, heart disease, stroke, and cancer are all closely linked together. Having one, increases the risk of having or developing another.
What are the health benefits of lower GI foods?
Compared to a higher GI food, in general, low GI foods will leave you feeling fuller, longer. It can be a vaulable tool in selecting carbohydrates that help control blood sugar levels and may help assist in managing body weight.
How do I know what food are low GI?
There are a lot of resources available online, but in general look for whole unprocessed foods; wholegrain bread instead of white, long brown rice instead of short grain or white, oatmeal instead of rice krispies. The longer it takes to breakdown food, the better. This doesn’t mean that you have to avoid high GI foods, because they may contain lots of great nutrients (example, potatoes). If you are going to eat a high GI food and are concerned about your blood sugar, try eating some protein or another high fiber carbohydrate in combination with the high GI food.
What is the difference between Glycemic Load and Glycemic Index?
Glycemix Index tells you how quickly a carbohydrate in a food will raise your blood sugar. The Glycemic Load gives us an even better picture because it give us information on how much of of the carbohydrate exisits in a specific food. A great example that Jawesome told me about was watermelon.
Watermelon has a GI of 72 but the fact is that there isn’t actually a lot (quantity wise) of carbohydrate in the fruit. So you would need to eat A LOT of watermelon to see a blood sugar rise – in fact is has a load of only 4 (out of a total of 60). This chart gives a nice summary:
Check back for tomorrow when The Health Junction continues the Worldy Nutrition Series with a stop in Europe.
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