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Glycemic Index: How it works!

by Josephine Andrews
Published: Last Updated on 226 views

The glycemic index indicates how a carbohydrate-containing food affects blood sugar levels. The following applies: the lower the GI, the less the blood sugar level rises. However, the glycemic index is controversial. Read here whether a diet based on the glycemic index prevents obesity and diseases and which foods have a high or low value.

Glycemic Index: what is it?

The glycemic index, also known as the GI or Glyx index, was designed in the 1980s as part of diabetes research. The idea behind it: With its help, carbohydrate-rich foods can be better compared with one another in terms of their effect on blood sugar levels.

The GI specifically indicates how long and how high the blood sugar level rises after eating a food. The following applies: the lower the GI of a food, the slower the blood sugar level rises. Therefore, according to the theory, a low GI diet should also protect against coronary heart diseases such as heart attacks as well as diabetes and obesity.

Glycemic index is controversial

There are now numerous guides that propagate the so-called GLYX diets. Institutions such as the World Health Organization (WHO) also see advantages in a diet that includes foods with a low glycemic index.

In fact, the GI provides orientation for a healthy, figure-friendly diet. However, not anymore. Because the actual glycemic index of a food can be very different. This depends, among other things, on the composition of the meal, the preparation of the product, the amount consumed and the individual blood sugar level.

The glycemic index of potatoes, for example, changes depending on whether they are eaten raw, cooked or mashed. In general, cooked foods tend to have a higher GI because the carbohydrates in them are more easily metabolized.

No recommendation from the DGE

The German Society for Nutrition (DGE) and the European Food Safety Authority (EFSA) do not give any recommendations regarding a diet based on the glycemic index.

For endurance athletes in particular, it is often beneficial to consciously consume food with a high Glyx index. Because during a competition, the glycogen stores, the most important source of energy, can be quickly replenished with such products.

Glycemic index: how is it calculated?

To determine the glycemic index, it is measured how high and how long the blood sugar level rises after eating 50 grams of carbohydrates from the respective food. The result is given in percent.

A reference value with a glycemic index of 100 percent is 50 grams of the simple sugar glucose. A glycemic index of more than 70 percent is considered high, a GI of 55 to 70 percent is considered moderate, and foods with less than 55 percent have a low value.

Glycemic index of food

The food can be divided into “high glycemic index”, “medium glycemic index” and “low glycemic index”. Fruit is in all categories, but is generally considered recommended (“5 a day”).

Among the top GI foods are dates and ready-to-eat mashed potatoes. On the other hand, peanuts and yoghurt have a low value. We have put together an overview for you in the following tables.

Foods with a high glycemic index

Foods that cause blood sugar levels to rise quickly include:

groceries Glycemic Index (list sorted by decreasing GI-%)
dates (dried) 103
Mashed Potatoes (Instant) 87
potato (baked) 85
Cornflakes 81
Litschis (Dose) 79
Porridge (Instant) 79
potato (cooked) 78
waffles 76
watermelon 76
French fries 75
Whole grain bread 74
White bread 73
white rice 73
cracker 71
Apricots (can) 64
raisins 64
figs (dried) 61
Pineapple 59
Papaya 59
Muesli 57

Foods with a low glycemic index

Some foods hardly cause the blood sugar level to rise. A selection of these is compiled below:

groceries Glycemic Index (list sorted by decreasing GI-%)
Kiwi 53
banana (overripe) 51
Mango 51
Chapati 52
Mango 51
orange juice 50
Strawberry jam 49
spaghetti (white) 49
Peas 48
On a cake 46
Orange 43
dates (fresh) 42
peach 42
Apple juice 41
carrots (cooked) 39
lenses 39
yogurt 27
peanuts 14

Glycemic Index: Restrictions!

Just looking at the GI and then shaping the diet is not recommended. Because there are several points to consider:

  • Not only the carbohydrate aspect is relevant for a healthy diet. What is the composition of a food in terms of table sugar, fructose and fats, for example?
  • How much was the food processed and prepared?
  • What part does the food make up in the complete meal? Is it the main ingredient or, for example, just an accompaniment?
  • Animal protein has a low GI. However, high meat consumption also has adverse effects on the body and the climate.

Glycemic Index and Glycemic Load

The concept of the glycemic load (also: glycemic load or GL) was introduced to determine the quantity of carbohydrates in a food in addition to the quality.

A distortion is corrected by the glycemic load. Because potatoes, pineapple, watermelons or papaya also have a comparatively high glycemic index, so they should be classified as unhealthy like white bread.

However, the GI reference value always refers to 50 grams of carbohydrates. To come up with it for pineapple or watermelon, you would have to eat vast amounts of the respective fruit – which is very unlikely in everyday life.

Specifically: A watermelon and a donut have the same glycemic index of 76. However, a portion of watermelon contains only eleven grams of carbohydrates, whereas the pastry has 23 grams.

The glycemic load is calculated using the following formula:

GI of food x available carbohydrates of food per serving: 100

So in the case of a slice of white bread (GI: 73) that would be GL: 0.73 x 14 = 10.2

A high GL is greater than 20, a medium 11 to 19, and a low GL is less than 10.

Below are a few examples of the GI and GL ratios of different food groups:

groceries GI GL
glucose 100 10
Baguette 95 15
white rice 87 37
French fries 75 22
Wholemeal bread (fine) 70 9
Rotate Bete 64 5
Pineapple 59 7
oatmeal 55 3
Brown rice 55 18
Most 53 7
Wholemeal bread (whole grain) 52 10
Salt potatoes 50 14
carrots 47 3
Paraboiled Reis 47 17
Apple 38 6
Spaghetti (weiss, al dente) 38 18

Glycemic index: health implications

There are studies that indicate that there is a link between the development of type 2 diabetes and high GI or high GL diets. However, this has not been scientifically proven.

However, if someone already suffers from diabetes, a diet with a focus on foods with a low glycemic index is very beneficial: in studies, the long-term blood sugar control of the subjects (type 1 and 2 diabetes) improved by around ten percent after the glycemic index of the diet had dropped by an average was reduced by 20 percent.

An EPIC study also showed that abdominal obesity (visceral obesity) is significantly related to GI. Conversely, this does not mean that a low GI diet will cause you to lose weight. For example, foods high in fructose, such as fruit, often have a low GI, but they can still lead to obesity.

Lose weight with the Glyx diet

Foods with a low glyx value and an exercise program form the basis of the glyx diet . She classifies foods according to their effect on insulin levels and marks them in color in the traffic light system. Foods that are in the red zone have a high GI score. In addition to toast, this also includes foods such as pumpkin .

You can read about whether you can lose weight healthily and effectively with a Glyx diet in the Glyx diet .

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