Glycemic index: definition and classification of foods

Below, the main terms essential to understanding the article:

• Blood sugar : blood sugar corresponds to the concentration of glucose (simple sugar) present in the blood (not stored or used by cells).

• Glycemic index (GI): criterion for classifying foods according to their ability to raise blood sugar levels, within two hours after ingestion. This notion tells us the speed of digestion and absorption of carbohydrates before entering the bloodstream. The glycemic index is equivalent to measuring the blood sugar level of 50 g of carbohydrates in a food compared to 50 g of glucose. Generally speaking, foods are classified on a scale going from 0 to 100. This scale is divided into three categories: from 0 to 39 we find foods with a low glycemic index, from 40 to 59 foods with a moderate glycemic index and 60 to 100 foods with a high glycemic index. Download the glycemic index table of foods in PDF version.

• High glycemic index (GHI): a high glycemic index corresponds to a score greater than or equal to 60. A food with an IGH quickly and strongly raises blood sugar (hyperglycemia).

• Moderate glycemic index (IGM) : an average or moderate glycemic index corresponds to a score less than 60 and greater than or equal to 40. After ingesting a food with an IGM, blood sugar levels rise moderately and over a longer period of time.

• Low glycemic index (IGB, or mega low food) : a low glycemic index corresponds to a score less than 40. IGB foods increase blood sugar levels little, over a longer period of time.

• Glycemic load (GL) : the glycemic load observes the overall impact of blood sugar levels when ingesting a portion of a food. Indeed, it is based on the glycemic index of a food by integrating the notions of quantity consumed.

• Insulin: hormone secreted by the pancreas in response to an increase in blood sugar (hyperglycemia). Its role is to reduce blood sugar to restore it within normal limits: it is a hypoglycemic hormone.

• Glycemic index from 0 to 10: Stevia, Dried seaweed, Yacon syrup, Spice, Shellfish, Vinegar, Avocado.

• Glycemic index from 11 to 20: Physalis, Rhubarb, Red fruit (currant, blackcurrant, blackberry, etc.), Most fresh vegetables, Bran (wheat or oat), Dried vegetable, Soya and its derivatives, Nut, Seed, Sprouted seed, Syrup agave, Carob powder, Acerola, Cocoa powder (no added sugar), Dark chocolate (up to 80% cocoa), Fructose.

• Glycemic index from 21 to 30: Cherry, Strawberry, Blueberry, Goji berry, Hummus, Oilseed puree, Dark chocolate (up. 70% cocoa), Apricot, Garlic, Beetroot (raw), Green beans, Tomato, Milk (cow, sheep, goat, etc.), Cottage cheese (sugar-free), Vegetable milk (no added sugar), Soy-based yogurt.

• Glycemic index from 31 to 39: Most fresh fruit, Tomato sauce (no sugar), Dried apricot, Yogurt (no sugar), Quinoa, Coconut flour, Chickpea flour, Mustard (no added sugar), Yeast, Prune.

• Glycemic index from 40 to 50: Dried fig, Sweetened yogurt, Oat flakes, Wholemeal dough al dente cooking, Pumpernickel (black bread), Buckwheat, Sesame puree (tahini), Raw cider, Coconut milk, Lactose, Falafel, Peach, Fruit juice, Pineapple, Coconut, Grapes, Peas, Prepared tomato sauce, Wheat pre-cooked (Ebly type), Spelled, Seed bread, Wholemeal bread, White cooking dough al dente, Sweet potato, Banana, Compote (no added sugar), Persimmon, Kiwi, Litchi, Buckwheat pancake, Muesli (sugar-free), Wholemeal pasta, Wholegrain rice, Wholemeal semolina, Industrial sauce, Surimi.

• Glycemic index from 51 to 59 : Chestnut, Coconut sugar, Date, Bulgur, Semi-wholemeal paste, Red rice, Semi-wholegrain rice, Fruits in syrup, Spread, Ketchup, Sushi, Cocoa powder (added sugars), Pearl barley.

• Glycemic index from 60 to 70 : Banana (ripe), Compote (added sugars), Melon, Wholemeal flour, Pastry, White semolina, Bean, Fruit nectar, Caramel, Milk chocolate, Ice cream, Sweetened condensed milk, Beetroot (cooked), Raisin, Dough well-cooked white potato, Potato cooked in its skin (in its coat), Soda, Jam, Maple syrup, Sorbet, Date (soaked in glucose syrup), Corn starch, Cookie, Breakfast cereal , Crisps, Rice noodle, White long rice, Sugar (white, muscovado, roux), Chocolate bar, Molasses.

• Glycemic index from 71 to 80 : Watermelon, Squash, Rusk, Fresh pasta, Confectionery.

• Glycemic index from 81 to 90 : Instant oatmeal, Sliced ​​bread, Carrot (cooked), Turnip (cooked), Celery root (cooked), Parsnip (cooked), Corn flakes, White flour, Puffed rice cake, Cooked potato, Popcorn (sugar-free), Cooked tapioca, Rice milk, White bread, Mashed potatoes, Honey.

• Glycemic index from 91 to 100 (and more) : French fries, Sticky rice, Syrup to dilute, Glucose syrup, Beer.

CG = [GI x amount of carbohydrates in a serving of food (g)]/100

The glycemic load of a food is considered low when it is less than 10, medium if it is between 11 and 19, and high when it is greater than or equal to 20.

Here is an example of glycemic loads based on their portions consumed:

Ultimately, theglycemic index is an imperfect concept which leads us to think that we must ban high GI foods. However, everything is a question of balance: no food should be eliminated. There glycemic load allows you to assess the quality and quantity of carbohydrates in a food by adapting to daily life.

In excess, foods with IGH are real poisons for the body. Indeed, after ingestion of the latter, blood sugar levels increase suddenly. Faced with hyperglycemia, the pancreas secretes insulin with the aim of restoring normal blood sugar levels. Insulin causes glucose in the blood to migrate into cells targets for storing it, particularly in the form of fat in adipose cells. However, the greater the hyperglycemia, the more the insulin secretion is important. Consequently, severe hyperglycemia leads to a sudden drop in it due to “hypersecretion of insulin”: reactive hypoglycemia. Very quickly, we go from one extreme to the other.

In the short term, hyper-variations in blood sugar result in fatigue, irritability and desires irrepressible to eat (signals sent by our body in response to reactive hypoglycemia to allow it to return to normal blood sugar levels). We are talking about “sweet cravings” which can follow one another throughout the day if we only meet these needs with high GI foods.

Long-term, a diet with chronic IGH can lead to intestinal dysbiosis, which encourages the onset of chronic inflammatory pathologies. Furthermore, IGH will promote the establishment of insulin resistance and thewe observe an increase in the prevalence of cardiovascular pathologies, overweight, obesity, etc. Above all, it is the main (if not the only) cause of type 2 diabetes. Concerning this pathology, knowledge of the glycemic power of foods is necessary to balance blood sugar levels.

Therefore, the glycemic index and glycemic load are fundamental values prevention and management of numerous pathologies.

As you will have understood, the glycemic index is an essential concept if we wish to protect ourselves from various disorders. However, we do not recommend that youUse this table to exclude from your diet all foods with too high a GI. You then risk unbalancing your diet with equally detrimental risks for your health. Let us also remember that the glycemic index is measured with an isolated food, without considering the bolus and concomitant digestion of other foods. Which does not correspond to a balanced and, above all, varied diet! 

From these facts, it is all the more interesting to play on the factors modulating the glycemic index (consequently, the glycemic load too) to obtain a diet with a low glycemic index, diversified and adaptable to your daily life. Indeed, certain culinary preparations or food combinations make it possible to reduce the glycemic index of a food.
Here are the main factors for variation in the glycemic index:

• The nature of carbohydrates : each carbohydrate has its own glycemic index: lactose is an IGM, fructose is an IGB, non-resistant starch or glucose are IGH. These scores depend on different factors, such as the size of the sugars (simple or complex), the activity and amount of enzymes available, etc. Generally speaking, simple and refined sugars have a high, or even very high, glycemic index. It is therefore essential not to consume them alone (snacking), outside of meals and first thing in the morning, at breakfast. Example: Sucrose (white sugar), sweetened drinks and confectionery have high glycemic indices.

• The presence of fiber : fiber cannot be digested and absorbed by the body. As a result, they hinder the access of enzymes to sugars, which slows down the absorption of sugars and lowers the glycemic index. Example 1: white pasta has a higher glycemic index than wholemeal pasta. Example 2: fruit juices have a higher glycemic index than fresh fruit.

• The presence of proteins and lipids : these macronutrients are metabolized by the body, but their presence within the digestive tract limits the access of carbohydrate enzymes and slows gastric emptying. All this slows down the absorption of carbohydrates and reduces the glycemic index. Example 1: soy cream (slightly richer in lipids) has a lower glycemic index than soy milk (almost devoid of lipids). Example 2: a slice of buttered bread has a lower glycemic index than a slice of bread alone. 

• The texture : mixing or grinding a food increases its glycemic index. In fact, softening the texture of a food facilitates digestive work and denatures the fibers. Thus, food is more available for enzymes: digestion and absorption is faster. Example: mashed potatoes have a higher glycemic index than boiled potatoes.

• Blowing : blowing changes the nature of the carbohydrates: complex carbohydrates become simple carbohydrates. This industrial step facilitates digestive work, which increases the glycemic index. Example: puffed rice cakes have a higher glycemic index than white rice.

• The cooking : cooking is a pre-digestion of food. Indeed, under the effect of heat, complex carbohydrates are transformed into simple carbohydrates. Thus, cooking foods for too long increases the glycemic index. Example: white pasta cooked al dente has a lower glycemic index than overcooked white pasta.

• Acidity : acidity slows gastric emptying, which slows the digestion of carbohydrates. For this reason, addacidic foods (for example, vinegar from salad dressing) helps to lower the GI of the meal.

• Maturity of plants : the carbohydrate composition of fruits and vegetables changes depending on their level of maturity. In fact, the more mature the plants are, the more their complex carbohydrates become simple carbohydrates. This phenomenon is explained by the presence of carbohydrate enzymes naturally present in plants. Example: ripe bananas have a higher glycemic index than green bananas.

• Starch cooling: cooling the starch lowers the glycemic index of starchy foods. Indeed, after cooking, when the temperature drops, the starch naturally takes on a so-called crystalline structure: this is the retrogradation of the starch. The retrogradation of starch makes it resistant to enzymatic work, we then speak of resistant starch. The latter behaves like a fermentable plant fiber, so it is virtually unaffected by digestion, which reduces the glycemic index of the cooled food. Example: potatoes cooked and then cooled have a lower glycemic index than potatoes eaten cooked.