Carbohydrates: how important is the glycaemic index?

Carbohydrates have a bad reputation. They are branded as fattening and are notorious for causing diseases such as obesity and diabetes. Yet carbohydrates are important for our bodies. In addition to energy, carbohydrate-rich foods usually also providevitamins, minerals and fibre. Some nutrition experts (including the German Nutrition Society) therefore recommend covering more than 50% of our daily calorie requirements with carbohydrates. In today's blog post, we explain the role of the glycaemic index in this context.

Not all carbohydrates are the same

So should you ban carbohydrates from your diet or eat more? To answer this question, we need to take a closer look at the group of carbohydrates Because not all carbohydrates are the same In this context, the two terms bad and good carbohydrates are often used. The first group includes, for example, household sugar (sucrose), glucose (dextrose) or white flour. Good or so-called complex carbohydrates, on the other hand, are provided by wholemeal products, vegetables and pulses. The body digests these more slowly, which means that the blood sugar level rises more slowly and we stay full for longer . Bad carbohydrates, on the other hand, are broken down quickly during digestion and cause the blood sugar level to rise sharply. Unfortunately, this also means that hunger quickly returns.

Glycaemic index and glycaemic load

Whenever the topic of good and bad carbohydrates comes up, sooner or later a term appears:The glycaemic index (GI). It is an important component of diet trends such as the Montignac and Logi methods or the Glyx diet. The glycaemic index indicates how strongly a carbohydrate-containing food influences the blood sugar level So does the GI help to differentiate between good and bad carbohydrates? Unfortunately, only to a limited extent, as it is only calculated based on the amount of food that contains 50 grams of carbohydrates. For watermelon you need about a kilo, for bread made from white flour 100 grams is enough. However, both foods have almost the same glycaemic index. This shows the weakness of the GI: the typical amount of a product consumed is not taken into account in the calculation. Unfortunately, the glycaemic index is therefore not really useful in practice. The Glycaemic Load (GL) is more meaningful. This also takes into account the carbohydrates per portion, which makes it much easier to compare different foods.

Why is a high glycaemic index bad for our body?

A high glycaemic index is synonymous with a high blood sugar level and therefore also with a high insulin secretion. This is because the body's cells need insulin in order to absorb glucose from the blood. The pancreas releases the hormone after eating a carbohydrate-rich meal and the blood sugar level drops. It's actually a perfect control loop. If it weren't for our current eating habits:Sweet drinks, white flour, sugar and the like cause blood sugar levels and thus insulin secretion to constantly shoot up. At the same time, we do not exercise enough and do not use up the energy we consume. Obesity and type 2 diabetes are the result. It is therefore not surprising that a diet with a high glycaemic index is said to increase the risk of obesity and type 2 diabetes . However, there is no clear scientific evidence for this.

In addition to the GI or GL of an individual food, the overall composition of the meal consumed also plays a role. Fat, protein and fibre because it also influences carbohydrate absorption and therefore blood sugar levels. The method of preparation also has an effect on the GI: French fries, for example, have a much higher glycaemic index than boiled potatoes. The glycaemic index is also not a fixed value, but varies from person to person.

• www.dge.de/wissenschaft/referenzwerte/kohlenhydrate-ballaststoffe/
• www.verbraucherzentrale.de/wissen/lebensmittel/schlankheitsmittel-und-diaeten/glykaemischer-index-gi-und-glykaemische-last-gl-11176
• DGE statement. Glycaemic index and glycaemic load - a concept relevant to the nutritional practice of healthy people? Ernährungs Umschau 2013, 1:M26-38