The glycemic index is a method created specifically to classify foods according to their influence on blood sugar. This is an attempt to measure how a specific food affects the level of sugar present in the blood.
When you start consuming food and it passes through the intestines, the blood sugar value will vary. This variation depends on the nutritional value of the food we eat. For example, the blood sugar level of a person who ate sweets will be different than that of a person who ate noodles.
The glycemic index thus tries to reflect the ability of foods to increase blood sugar levels. It is not just a simple number, but rather a mathematical formula created for this purpose.
According to this system, there are two types of food:
- Foods with a low glycemic index: the type that does not increase blood sugar levels as much immediately after ingestion. In addition, the increase it produces lasts longer.
- Foods with a high glycemic index: this type of food leads to an immediately high blood sugar level in the body, but it does not last long.
The formula was created in 1981 and the complete tables in 1995. These have more than 500 types of food classified according to the glycemic index. We also have the international table from 2002 which was proposed by the researcher Fo ster and his team. It is currently the most accepted table.
Factors affecting the glycemic index
It is important to understand that the glycemic index is not the same as the carbohydrates present in foods. The effect it has on blood sugar is one thing, and the nutritional composition is another (this confusion often works against its purpose).
The official classification takes place in three groups, and the value of the glycemic index in a food is given by:
1. The type of simple sugars the food consists of
As we said earlier, the nutritional composition does not have a direct effect on blood sugar. Potatoes contain, for example, a type of simple sugars that differs from the type found in milk. The body will therefore react differently and treat them at different times.
2. The presence of other nutrients
Sugar is not isolated in food, but is there in connection with other substances such as fat. The sugar in nuts, for example, is there along with fat and dietary fiber. The body therefore spends more time excreting the sugar and processing it.
3. How the food is processed
Fried, cooked or fried foods do not have the same effect on blood sugar. If the food has been stored in the refrigerator or freezer, the final effect will also be different. We know, for example, that mashed potatoes have a higher glycemic index than a fried potato.
Fruit juice also has a higher glycemic index than a whole fruit. “Al dente” pasta has a lower index than overcooked pasta.
Values used in the glycemic index
The numbers used come from laboratory tests and formulas. For our daily use, it is not necessary to understand how to perform the calculations or how scientists arrived at this formula.
However, we can say that it is a proportional measure of the rate at which the carbohydrates in the foods we eat manifest themselves in the form of blood sugar. It is therefore proportional because the reference value is always the same as for pure glucose.
Pure glucose has a value of 100, and based on this reference we can establish the indices of the rest of the foods and create three general groups:
- Low glycemic index: these are foods with a value between 1 and 55.
- Medium glycemic index: these foods have a value between 56 and 69.
- High glycemic index: this applies to all foods with a value higher than 70.
The higher the level, the faster your blood sugar will rise after ingestion. On the other hand, foods with a low value will not have a significant effect on blood sugar levels.
Let us again emphasize that this value does not reflect the nutritional value of a particular food. It does not give us information about fats and kilocalories. It mainly gives us the specific sugar load the food contains.
How does the glycemic index affect our daily lives?
As we have said before, the measure we are talking about is not the only thing we have to take into account. It is a measurement that can help us map a diabetic diet, but always in combination with other factors.
One value that helps to complement this is the glycemic load that measures the quality and amount of carbohydrates in a serving of food. A commercial muesli bar has a high glycemic index but a low glycemic load. This is because the portions are always small.
In addition, the food varies when it comes to foods prepared by professionals. The glycemic index in these cases is derived from the combination. For example, you can compensate for a high-value portion of food if you eat the same dish with another with a low glycemic index.
Similarly, there are several meals in one day, so the individual glycemic indices are combined. We know that a meal with a low glycemic index is able to improve the glucose assimilation of the next meal as a cumulative effect.
In the presence of metabolic diseases such as diabetes, it is always important to follow the guidance of a nutritionist when it comes to diet. By consulting these professionals, you can find answers to many of the questions you have regarding your eating habits.