Wednesday, February 1, 2012

The Glycemic Load - It Ain't Heavy! by Andrew Mason

Some people think that the glycemic index has limitations, as it's only based on a calculation of a particular type of carbohydrate in a set portion. The index was compiled by allocating specific portions to volunteers, 50 g at a time, to form the basis of a calculation. Of course, it is very rare for us to eat measured portions anyway and 50 g, when applied to certain types of food, is a real abnormality. The research team needed to markedly increase or decrease the actual quantity of certain types of food, so that they could come close to the nominal 50 g measurement.

Because the index, taken by itself, does not reflect a life in the real world, scientists were forced to develop and factor in a mechanism, called the glycemic load.

The glycemic load takes into account the particular portion size as well when assessing a carbohydrate's impact. The glycemic index is first divided by a factor of 100 and multiplied by the carbohydrate content according to the serving size. From this, we can get a much more usable reading and we are able to select the carbohydrate for a balanced diet, based on its glycemic load reading, rather than its straightforward carbohydrate content.

The glycemic index has certainly been groundbreaking, since its invention by two doctors based at the University of Toronto. The underlying philosophy suggests that certain carbohydrates will be more easily digested by our systems than others and we can suffer from a temporary rise in blood glucose levels, according to this relative digestion speed. The doctors discovered that such an imbalance could lead to health problems such as heart disease and diabetes. Blood glucose level spikes create hunger pangs and sugar cravings, which in short order can lead to weight problems. Many dietitians welcomed the glycemic index and developed plans based on food rankings toward the bottom of the list.

If you are planning your diet, pay attention to those foods that have a positive glycemic load, so that you can see the value of the carbohydrate in the portion. You should bear in mind that foods that rank toward the top of the index may indeed have a much lower reading when they are consumed in more common portions.

On the glycemic index, foods that rank at 20 on the scale of 0 to 100 are classified as "low." The glycemic load has its own index, and in this case foods are classified as low when they are below 10, medium up to 20 and higher thereafter.

Consider the potato. It has a glycemic index of 50 in general. If we apply a factor of 20% based on its carbohydrate content by portion size, its glycemic load would factor at 10. You can see how important portion control is now and can understand why it is such a significant issue for the typical American. In reality, few have a diet that is regulated by portion size. We can see this graphically if we just stand outside a restaurant and watch people carrying those "doggy" bags home at the end of a meal!