GLYCEMIC INDEX Vs. GLUCEMIC LOAD
The glycemic index is a concept that is very widespread both among athletes and among those people who want to take care of their diet or do a weight loss program. But currently there is another concept that, without being so well known, is becoming more and more relevant in these areas, it is the glycemic load.
The objective of this text is to define both terms and compare them, since, although they have very similar names, they can get confused.
GLYCEMIC INDEX (GI)
The concept of the glycemic index appeared in the 1980s when it was observed that foods that had the same amount of carbohydrates had different effects on the level of sugar in the blood.
When we eat, the body breaks down most of the food and obtains carbohydrates from
carbon, including glucose. This molecule is the main source of energy for cells.
After eating, the time it takes for the body to convert carbohydrates and release glucose into the bloodstream varies, depending on the type of carbohydrate and the food that contains it. Some foods have carbohydrates that cause blood glucose levels to rise rapidly, while others have a slower effect.
The GI measures the speed with which a food is able to increase blood glucose levels. Higher GI foods raise blood sugar faster than lower glycemic index foods. Taking pure glucose as a reference value with a value of 100.
Foods GI HIGH GI> 70 Foods with a MEDIUM GI 69 = GI = 56 Foods with a LOW GI <55
GLUCEMIC LOAD (CG)
On the other hand, the GI does not take into account that when we eat complex foods, their content is not only carbohydrates. In the case of pure glucose, this does not matter as it is a 100% carbohydrate. But how to compare glucose with a food that in addition to carbohydrates has proteins, lipids, water, fiber, vitamins, minerals, etc …?
To answer this question, the concept of glycemic load (GL) appears. The glycemic load is defined as the product of the GI by the amount of assimilable carbohydrates contained in the proportion of food used. In a simple way we could say that while the GI refers to the speed with which a type of carbohydrate is absorbed and passes into the blood, the glycemic load refers to the intensity of the insulin response that the food will provoke that we have taken.
Foods GL HIGH GL> 20 Foods with GL MEDIUM 19 = GI = 11 Foods with GL LOW GL <10
INFLUCENCE OF GI AND GL ON OUR DIET
Once both concepts are clarified, how can this help us in our daily lives? What if we do sports?
In our daily diet, a foray of foods with a low glycemic index is recommended (rice, potatoes, pasta, legumes, etc …) since for its metabolism the secretion of large amounts of insulin is not necessary but with small amounts, they are absorbed little by little, so the feeling of hunger is controlled for a longer time.
In the case of athletes, it is important to know how to choose foods with a medium GI and medium-low GL for during exercise as this guarantees a correct energy intake as well as a good absorption and progressive use of carbohydrates. We also avoid insulin spikes and hypoglycemia. After exercise, it is necessary to replenish all our carbohydrate stores, so we must know how to choose foods with a high GI and GL.
PRACTICAL CASES: WATERMELON, WHITE BREAD, PASTA and WHOLE PASTA.
To finish consolidating these two concepts, let’s put several examples: the case of watermelon, white bread, pasta and wholemeal pasta.
Watermelon (91% water, 4.5% HC, 0.5% protein, 0.3% lipid, 0.3% fiber) is a food that contains a high GI index value (72) since it is digested and absorbed very quickly. But if we look at its glycemic load value we see that it is low (5) since it only contains 6 grams of carbohydrates for every 100g of watermelon, it is not necessary to secrete much insulin to metabolize this amount of CH.
Another example to highlight would be white bread with a GI value of 70. A portion of 30 grams of white bread has a glycemic load value of 7. This wide difference between the GI and GL values is due to the fact that cereals that make up this food contain complex carbohydrates which reach the blood slowly since digestive enzymes have to destroy a very high amount of bonds in order to be metabolized. Much less insulin is needed. We also take into account that the amount of “usable” carbohydrates yields 40%, the rest are fibers, proteins, fats, minerals, etc.
Let us now look at the example of pasta as a case in which the glycemic load can be modified. Pasta is largely made up of semolina flour, which is a little refined flour that comes from wheat, but also from other cereals such as oats or rye. This food is made up of complex carbohydrates of the starch type. To be digested, the action of amylase enzymes is necessary to hydrolyze these glucose chains.
When we cook pasta, we are doing the work of the enzymes, therefore, when we eat them, the work necessary to assimilate them is much less, and therefore the insulin response (CG) increases. Therefore, for a pasta to be ready to eat and its effect is that of a slow release of glucose in the blood (and therefore a progressive hormonal response) it must be slightly hard (10 minutes of cooking), which is called ” al dente ”. For this reason, the longer we cook the pasta, the glycemic load value will progressively increase.
To finish, a fourth example, whole wheat pasta . Wholegrain pasta conserves the fiber of the bran (the flour is even less refined than in the previous case, hence its brown color) and they provide fewer calories than common pasta, by maintaining and preserving the properties of the cereal, they contain a greater amount of fiber. By having a greater amount of fiber, it contains in the same proportion less “usable” carbohydrate, so the insulin response is lower (lower CG).
Glycemic load and glycemic index are two terms that are confused by their similar name, the second being better known and more widespread than the first. Many people have heard of the glycemic index but very little about the glycemic load.
The knowledge of both concepts, allows us to choose the adequate contribution of carbohydrates for our daily life. This is very useful for those who want to control their diet for pleasure or illness, as is the case with diabetics.