Glycemic Index Vs Glycemic Load: Understanding The Difference by Andrew Mason

When the glycemic index was first suggested, many people thought that it had limitations. After all, it was just a basic calculation of the effects of a particular type of carb, in a given portion. The portion had to be universal - 50g. When the index was compiled, volunteers had to consume each of these different carbs to form a calculation. It is very rare for us to eat measured portions as it is, and a 50g serving of certain types of food is really unusual. When the research team was putting these experiments together, they sometimes had to significantly increase the actual quantity of certain food types, in order to come up to the 50g universal measurement.

This does not, of course, reflect life in the real world and the whole purpose of the index development was to help people regulate what they eat. Therefore, scientists have developed a further mechanism, called the glycemic load, to help us understand.

Portion size is assessed in addition to food type when we calculate the glycemic load. To do this, we have to divide by using a factor of 100 before multiplying by the carbohydrate content of the serving size. Now we have a much more sensible reading and we're able to use these readings to construct a balanced diet based on the glycemic load ranking. We no longer have to guess, based on a straightforward carbohydrate content makeup.

Two doctors at the University of Toronto were credited with the development of the glycemic index, a far-reaching achievement. They found that different types of carbohydrates are digested in different ways by our systems. Certain carbs cause a negative impact by temporarily raising blood glucose levels during the process of digestion. The doctors found that this could lead to health problems, most notably diabetes but also heart disease. If we don't regulate blood glucose levels we can suffer from hunger pangs and eat a very imbalanced diet, putting on weight as we do so. This is why the glycemic index is so favored by dietitians as they tell us to focus on foods at the bottom of the list.

Portion control is very important when planning a diet and this is why you should always think about the glycemic load rather than just the index. Remember that foods that are found at the top of the index may, when recalculated according to the load, be less stressful for you if consumed in more sensible portions.

The glycemic Index classifies foods with a ranking of 20 or less as low-impact. Remember that the glycemic load itself has a separate index, with "low" meaning below 10, medium at or below 20 and anything greater classified as "high."

To illustrate this we can consider the potato, which has a glycemic index of 50. We need to apply a factor of 20% to adjust to a sensible portion size and find that its glycemic load is now, in fact, just 10. This illustrates the importance of portion control and should be of particular relevance for the typical American diet. Few of us live according to regulated portion sizes, a sad fact of life that we can see in graphic detail if we watch people carrying those "doggie bags" out of the restaurant!