Glycemic Index: a mistaken tool to control your blood glucose level

Glycemic Index (GI) is frequently mentioned by nutritionist, doctors and other health physicians as a good indicator to manage blood glucose levels. Most people have heard about it and know that a low glycemic index is better for their health, but have you ever wondered why?

I did, and what I found in recent studies of NSCBI ( National Center for Biotechnology Information) that GI wasn’t a reliable index. Here are few points you should be aware of, if you are trying to control your blood sugar level.

FYI: Everyone should be aware that a constantly high blood sugar level increases your chances of developing diabetes and other metabolic diseases.


The concept of the GI was developed in 1981, by Doctor David Jenkins. Doctor Jenkins and his team were trying to find out which foods were most adapted for people with diabetes. They determined how carbs impact blood sugar after digestion.


Glycemic Index (GI) lists food by its effects on postprandial (occurring after a meal) blood glucose level compared to a reference food: glucose. Glucose has the maximum GI value: 100, all the other food will be evaluated on 100 (for example boiled potatoes have a 85 GI). GI can be influenced by many factors such as food processing, cooking and individual characteristics.

According to Doctor Jenkins study, food with a higher GI involves a higher postprandial blood sugar response. Higher blood sugar levels lead to higher insulin levels which is extremely dangerous for people with diabetes and only slightly dangerous for others.

Glycemic Index subdivision

Low GI (55 or less): Corn tortilla, spaghetti, barley, yogurt, orange juice, boiled carrots, lentils, chickpeas, fructose and most fruits.

Medium GI (56-69): Sweet potatoes, soda, honey, muesli, brown rice, quick oats.

High GI (70 or more): White bread, corn Flakes, white rice, rice milk, watermelon, potatoes boiled, rice crackers, glucose.


Interest of Glycemic Index

GI Graph

Graphic from


Recent studies from the American society of nutrition showed that High GI diet increased the chance of depression.

Low GI  diets are independently associated with a reduced risk of  diabetes and heart disease.

Low GI diets improve blood sugar management and insulin control

GI is highly involved in energy metabolization: a low GI meal will energize you for easily 4 hours. Therefore there is not a starving sensation, meaning no snacking.


Beans have a low glycemic index

On the other hand, High GI will make you feel hyper active, but watch out–your blood sugar level will rise and you’d better use it or it will be transformed into fat…

Watch out, High GI aliments are not always the best to get over a hypoglycemia crisis. Here are a few tips to get through it :Hypoglycemia and Sport: the keys to detect, cure and prevent low blood sugar symptoms

Lately, many studies about GI have been conducted but the results are not consistent. In my point of view, GI is an interesting tool but some others food factors are more relevant when monitoring your blood sugar levels.

Real factors to consider when monitoring blood sugar levels

  • Carbohydrate content should be the first thing you should be aware of. When you eat the same amount of honey or rice, you will not process the equal quantity of sugar.

Honey (100g)

White rice (100g)

Carbohydrates (g)



Honey contains almost 3x more sugar than white rice but his GI is lower than white rice.

  • Carbohydrate break down must be known. If you have 100ml of soda GI 59 or eat 100 g of potatoes GI 78.

Soda (100g)

Boiled potatoes (100g)

Carbohydrates (g)






Check it out, In a 100mL of soda 1/3 glass, you have 10 times more pure sugar than in 100g of boiled potatoes. Pure sugar goes directly to your veins, unlike starch, which needs times to be digested. Boiled potatoes contain more carbs of course but these are good carbs associated with vitamins, mineral. They will also help you to feel full instead of cola.

  • Macronutrients breakdown, If you eat the same quantity of mango or oatmeal, you will not receive the same nutrients. Basically, carbs associated with fat and protein take more time to be digested and your body will use the same carbs to process these two others nutrients.
  • Fibers are essential to control blood sugar levels. When ingested, they will form a “net” in your stomach and slow down the digestion. That’s why I recommend incorporating more legumes in your diet. For example: Chickpeas: A Healthy Bean To Incorporate In Your Recipes.
  • Food combination is a key point in blood sugar management. I worked a few months in a hospital with the diabetes department. One of the workshops consisted of preparing your own meal. We were explaining that quality is as important as quantity in food choices.

Look at these two different plates, which one will you choose if you want to avoid high blood sugar levels? Why?

Please comment and explain your choice

Collage food GI

Plate 1: fries, rice, steak and eggs  VS Plate 2: cabbage, tomatoes, olives, falafel


Glycemic Index gives clues about how the sugar in a specific food is breaking down in our body. But it is not a reliable index to manage blood sugar levels.  Someone with diabetes should completely avoid soda (GI 59) but has no reason to remove potatoes from his diet as long as he consume it in the right quantity. Be aware of your food choices: quantity and quality; think fibers and high quality carbs. Substitute High density food for high nutrient food and you will master sugar control in a snap.



Am J Clin Nutr. 2015 Aug;102(2):454-63. doi: 10.3945/ajcn.114.103846. Epub 2015 Jun 24.





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