Hi peeps ♡
As promised, here my next blog entry from my blog series 'sugar': The Glycemic Index!
As already explained in my previous blog entry "What is sugar and how is it metabolized?" carbohydrates are often divided - due to their different chemical composition - into simple and complex carbohydrates . As you already know, simple carbohydrates consist of one or two sugar molecules (monosaccharides and disaccharides ), while complex carbohydrates (polysaccharides) can be composed of many, even several thousand, sugar molecules. They are found in vegetables and pulses, for example. The body needs a lot of time to break down all these chains. That is why complex carbohydrates are digested more slowly. From a nutritional point of view, these foods are therefore more valuable than simple carbs (Gameau, 2015, p. 112).
In the early 1980s, an index was developed to explain how quickly different carbohydrates are digested and transported into the bloodstream. This index is called the Glycemic Index, glyx or GI and works like a food-rating (Gameau, 2015, p. 112): "The glycemic index rates food from 0 to 100, indicating how quickly a food is converted into blood sugar [...]" (Gameau, 2015, p. 113).
Foods with a high GI, are quickly digested and absorbed, which leads to a rapid rise in blood sugar. These foods that rank high on the GI scale are often found in processed carbohydrates and sugars. White bread, for example, has a GI of 95 and white rice a GI of 98 (Gameau, 2015, p. 112). Since these foods release more insulin, and lead to a sharp rise in blood sugar, as already explained above, they should be avoided or eaten in moderation. Meanwhile, foods with a low glycemic index are digested and absorbed at a much slower pace, and subsequently, cause a slower rise in blood sugar levels. These foods are typically rich in fiber, protein or fat. According to this principle, foods with a low GI generally healthier and should be eaten more often. However, there is a crucial catch here, which probably many people who are less familiar with the topic 'nutrition' are not aware of: there are some "unhealthy" foods with a very low GI (Gameau, 2015, p. 112 f.)!
How is this possible? Here is the explanation:
Ice cream, for example, has a GI of ３６ (!) , i.e. a relatively low glycemic index . Of course, this does not (!) mean that ice cream is healthy and should be eaten regularly. But why is the GI so low?
- First, the composition of the food plays a central role here (Diabetes Austria, 2006, p. １): ice cream consists not only of sugar, but also of fats and proteins. Since fats and proteins, unlike carbohydrates, do not directly affect blood sugar levels, they also lower the GI of ice cream. Meaning: when foods with a low GI are added to sugar or other carbs they lower their GI and make them look benign when in fact they are not.
- The other reason is that ice cream consists mainly of fructose. If you look at the table of foods down below, you will recognize that some sugary foods have a rather low GI. For example, table sugar has a lower GI than potatoes or white bread. That is because they all contain fructose. Fructose has an extremely low GI, of about 20 (see green list). This is because fructose does not raise blood sugar levels. As in the article "' Sugar Part II ' , glucose is always present in the blood because it is an important energy supplier for cells. Fructose, on the other hand, is transported to the liver, where it then causes trouble and can be responsible for fatty degeneration of the liver and many other negative effects. Fructose is not in the blood, my friends, it is in the liver! This is the only reason why some sugary foods have a relatively low GI. Not because they are healthy or harmless, but because they have little or no effect on blood sugar levels (Gameau, 2015, p. 113)! 'Fructose causes seven times as much cell damage as does glucose, because it binds to cellular proteins seven times faster; and it releases 100 times the number of oxygen radicals` (Lustig, 2013). So please be aware of that fact, when using the GI for weight loss!
The way food is processed and prepared can also change the GI(Diabetes Austria, 2006, p. 1): raw carrots , for example, have a relatively low GI 30, while cooked GI 85 . Due to their high GI, cooked carrots are more likely to be classified as potatoes or bread. This is important an information that can help if we want to lose weight! The GI also changes with corn (GI = 70) and popcorn (GI = 85) due to the preparation, although not as drastically as with carrotsDiabetes Austria, 2006, p. 5).
Thus, not all calories are the same: it makes a difference whether 100 calories of vegetables or 100 calories of chocolate are eaten, because the different structure of these carbohydrates also behaves differently in the body (Elmadfa, 2009, p. 74).
When is a GI value high?
Here the boundaries are not exactly defined, there are different opinions on this, but in general the following classification applies:
- GI greater than 70 = high, “bad” → red
- GI values between 50 and 70 = medium, okey → yellow
- GI less than 50 = low, “good” → green (Diabetes Austria, 2006, p. 5).
I alI have additionally marked the individual tables by using a traffic light system (red, yellow, green): red means that the GI is high, yellow medium and green indicates a low GI. Thus, the foods on the green list should be eaten more often and are suitable for weight loss, those on the yellow list are rather moderately suitable and the foods on the red list should only be consumed in moderation.
!! However, at this point I would like to point out once again that the exceptions mentioned above must be observed: sugar and foods containing sugar (except fruits and vegetables) are always to be considered RED and should therefore be avoided or consumed in moderation, no matter what list they are on !!
Foods with a low glycemic index
Figure 1: Food with a low glycemic index (Diabetes Austria, 2006, p. 5)
Foods with a medium glycemic index
Figure 2: Foods with a medium glycemic index (Diabetes Austria, 2006, p. 6)
Foods with a high glycemic index
Figure 3: Foods with a high glycemic index (Diabetes Austria, 2006, S. 7)
I hope that the article was exciting for you to read. The next one is coming soon ♡
Diabetes Austria (11.03.2006): Glycemic Index. https://diabetes-austria.com/fileadmin/diabetes_austria/downloads/glykaemischer_index.pdf. [accessed on 21.08.2020.].
Elmadfa, Ibrahim (2009): Nutrition. 2nd edition Stuttgart: Ulmer
Gameau Damon (2015). Voll Verzuckert. That sugar book. Wie uns die Lebensmittelindustrie dick macht und uns für dumm verkauft. Wege aus der Zuckerfalle. München: Gräfe und Unzer Verlag .. How the food industry makes us fat and fools us. Ways out of the sugar trap. Munich: Gräfe and Unzer Verla
Lustig Robert (21.10.2013.): Fructose: the poison index. The Guardian.https: //www.theguardian.com/commentisfree/2013/oct/21/fructose-poison-sugar-industry-pseudoscience. [accessed on 31.08.2020.]