Friday, February 25, 2011

Explaining the glycemic index

There must be hundreds, more probably thousands, of books available on the market devoted to the glycemic index. And if you Google ‘glycemic index’, you get over a million returns. So I will keep it simple. I will give you the basics, and you can ask questions afterwards, if you like, by leaving a comment. Everyone knows how to leave a comment, right? You click on the word 'comment' at the end of this post, and a comment box will pop up for you to fill in. Easy? Thank you.

The glycemic index (GI) is a rating of the carbohydrate content of a food, according to what impact the food in question has on blood-glucose levels, in comparison to a preset standard. The preset standard used is usually glucose = 100.

Foods with a GI in the range 70 - 100 are High GI. Anything between 55 - 70 is Intermediate GI. And anything lower than 55 is, of course, considered Low GI. We need to eat at least 50% of our carbohydrates from the Low GI group.

Foods with a high GI are digested and absorbed very quickly, releasing sugars (glucose) into the blood stream. This promotes an immediate and sometimes excessive insulin response. The insulin reduces the glucose levels in the blood stream by diverting the glucose to body tissue (muscles, organs), either for use now or by storing it as fat.

Eating high GI foods, then, produces what's known as a 'spike' - a lot of glucose is rapidly released into the blood stream and the insulin response removes the glucose from the blood stream just as fast. And you're hungry again an hour later, yes? Lots of glucose demands lots of insulin.

On the other hand, foods with a low GI are digested and absorbed more slowly, so that the body's demand for and release of insulin is retarded. You stay satisfied for longer.

Despite what I said about eating at least 50 % of our carbohydrates from the low GI group (and I still hold with that) we shouldn't eat low/no GI foods indiscriminately. Nor should we eat overly large portions of the healthy low/no GI foods - excess intake of any food can lead to weight gain (unless we're talking about broccoli or lettuce).

What we are aiming to achieve is good nutrition and weight management, without inopportune hunger pangs. We want (and need) all-day energy. We need to be able to cope with stress. We need to maintain our emotional equilibrium.

More on GI on Monday. See you then.

1 comment:

Teresa said...

Love it

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