What is GI? All you need to know about Glycemic Index

What is the glycemic index?

The glycemic index (GI) is a food-specific index that classifies carbohydrates according to their ability to raise blood sugar levels. Normal blood glucose levels are between 3.9 and 5.8 mmol/L. All carbohydrates cause, as a result, a certain increase in blood sugar levels. GI represents how slowly or quickly increases blood glucose levels over a period of time – usually two hours.

The glycemic index makes it possible to compare portions of foods that contain the same weight of carbohydrates according to their ability to raise blood sugar.

  • Fast-digesting carbohydrates with a high GI are those that cause blood sugar levels to rise swiftly and dramatically.
  • In contrast, those that digest slowly and don’t affect blood sugar levels have a low GI.

Table of glycemic indexes of some common foods


Since we have just seen that we cannot calculate it ourselves, to know what the GI of a food is. Therefore, you should consider using scientific GI tables from laboratory tests, one of the world’s GI specialists, Jennie Brand-Miller.

Jennie Brand-Miller and her team have examined the glycemic index of a variety of industrial products.

Foods with a glycemic index below 55 have a low glycemic index and are generally the healthiest, those between 56 and 69 have a moderate glycemic index, and foods with values from 70 have a high glycemic index, and should normally be avoided in the diet or consumed in moderation.

High-Carb Foods

The following is a list of the most popular low-, medium-, and high-glycemic carbohydrate foods:

Carbohydrate-rich foods
Low GI ≤ 55 Medium IG 56-69 High GI ≥ 70
All-Bran: 30 Brown rice: 68 White Rice: 73
Oats: 54 Couscous: 65 Gatorade isotonic drinks: 78
Milk chocolate: 43 Cassava flour: 61 Rice crackers: 87
Whole spaghetti: 49 Arepa (Corn flour): 60 Corn cereal type corn flakes: 81
Rice noodles: 53 Popcorn: 65 White wheat bread: 75
Whole wheat bread: 53 Soft drinks: 59 Tapioca: 70
Corn tortilla: 50 Muesli: 57 Cornstarch: 85
Barley: 30 Bread with grains: 53 Tacos: 70
Fructose: 15 Homemade pancakes: 66 Glucose: 103

Vegetables and legumes


The glycemic index of the main vegetables and legumes consumed daily is indicated in the following table:

Vegetables and legumes (general classification)
Low GI ≤ 55 Medium IG 56-69 High GI ≥ 70
Beans: 24 Steamed yam: 51 Mashed potatoes: 87
Lentils: 32 Cooked pumpkin: 64 Pope: 78
Cooked carrot: 39 Green banana: 55
Legume soup: 48 Turnips: 62
Cooked sweet corn: 52 Yucca: 55
Cooked soy: 20 Peas: 54
Grated raw carrot: 35 French frie: 63
Sweet potato with skin and cooked: 44 Beets: 64
Sweet potato without skin: 61


A fruit’s glycemic index might vary depending on its variety. As a result, the following table shows the glycemic index of the most common fruits taken daily:

Fruits (general classification)
Low GI ≤ 55 Medium IG 56-69 High GI ≥ 70
Apple: 36 Kiwi: 58 Watermelon: 76
Strawberries: 40 Papaya: 56
Orange: 43 Peach in syrup: 58
Unused apple juice: 44 Pineapple: 59
Orange Juice: 50 Grapes: 59
Banana: 51 Black cherries: 63
Mango: 51 Melon: 65
Apricot: 34 Dates: 62
Peach: 28 Raisins: 64
Pear: 33
Blueberries: 53
Plums: 53

Oilseeds, milk, and alternative drinks


They are all low glycemic index oilseeds such as nuts and seeds, however, it is important to consume them in moderation. An example of the GI of several oilseeds is shown in the table below.

Oilseeds (all are low GI)
Nuts:15 Merey/cashew/cashew: 25 Peanuts: 7

Besides oilseeds, low-glycemic-index milk and alternative drinks are listed in the following table:

Milk, alternative beverages (all are low GI)
Soy milk: 34 Skim milk: 37 Natural yogurt: 41
Whole milk: 39 Fermented milk: 46 Natural low-fat yogurt: 35

In order to prevent fat buildup in the body, enhance the sense of satiety, and decrease hunger in the body, meals should be cooked using low or medium glycemic index foods.

How to lower the glycemic index of a food?

There are various tricks to lower the GI of food:

  • Eat raw: GI of a steamed potato is quite high (88). On the other hand, when it is served as a salad, GI is only 58. In fact, the potato’s starch alters when it cools, becoming more resistant to digestion and releasing its glucose into the blood more slowly.
  • Try to add lemon juice or vinegar: By adding the equivalent of a teaspoon of lemon juice or vinegar to a dish, it appears to be able to drop blood sugar levels by 15 to 30%.
  • Use oat bran instead of flour in certain recipes (bread, cakes, pies, etc.): This raises the amount of soluble fiber in the preparation, which delays digestion and glucose absorption in the body.

Why favor carbohydrates with a low glycemic index?


As we’ve seen, the ingestion of food causes a rise in blood sugar. Moreover, in order for the body to function effectively, blood sugar levels must remain within certain limits. The body uses insulin to prevent blood sugar levels from rising too high. Immediately after carbohydrate consumption, the pancreas secretes insulin to allow cells to utilize glucose and prevent sugar from accumulating in the blood.

As food’s glycemic index (GI) increases, so does the blood sugar level and the amount of insulin released. In the long run, eating foods with a high glycemic index can cause the body’s cells to become less sensitive to insulin. This “resistance” to insulin makes it more effective, resulting in a sugar overflow. Diabetes type 2 and obesity are possible outcomes of insulin resistance.

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