Why low glycemic index diets do not work
Before I became a dietician – I was 250 lbs Roly-Poly. My favorite method of slimming was the low-glycemic diet, created by Michel Montignac.
The low GI diets, however, DO NOT work!
Well, they work – but only in the initial period when we are in the euphoria of the first successes. Then, however, we start to gain weight – even though we follow all the instructions. Why? Because the very assumption of the method is a mistake!
Before everything becomes clear, let’s get acquainted with the concepts of glycemia, high and low glycemic meals, glycemic index and glycemic load.
Let me start from scratch:
What is glycemia?
Glycemia (blood glucose) is nothing but the content (concentration) of glucose in the blood. It is measured in units of “mg/dL” expressing the amount of mg of glucose in 100 ml of blood.
Sometimes it is evaluated in mmol/L. (1 mmol/L = 18 mg/dL)
The correct blood glucose is 65-100 mg/dL *, and in half an hour after a meal 140-160 mg/dL (should not exceed 180 mg/dL; above 160 mg/dL glucose appears in the urine).
*) Sometimes, slightly different standards are adopted, but in this study I will refer to the above levels.
Let’s recall the standard glycemic curve:
And now – let’s analyze how it changes depending on what we eat.
Suppose I did not eat breakfast, because I overslept and then hurried. During the first break at work, my friend dragged me to the cafeteria and forced me to eat a big fruit jelly.
As it did not impress me, I accidentally ordered a vanilla cream puff, three lemon meringues and a raspberry foam cake.
After eating, blood glucose will rise to high values, which will provoke the pancreas to secrete a huge amount of insulin.
As the glucose concentration has risen sharply, the reaction caused by insulin will be equally rapid: Glucose will be removed from the blood with such power that its concentration in blood will fall below normal – for some time.
This is so-called “reactive hypoglycemia”. It is caused by a certain delay of the glycemic control mechanism: the drop in glucose was too fast for glucagon to work on time.
The more glycemic a meal is, the deeper the reactive hypoglycemia will follow. And this is our enemy: a hyperglycemic meal – the cause of many tragedies.
Let’s look at the section of the glycemic curve marked in blue. It covers the period during which the glucose concentration in our blood drops sharply (because insulin removes it from the blood).
This rapid decline is a very strong stimulus for the center of hunger in our brain. Why? Because the “Center of satiety and hunger” (situated in the hypothalamus) – responds more to CHANGES of blood glucose * than to the absolute blood glucose level.
*) Refers to changes in glucose concentrations between 1. the portal vein, collecting blood from the intestines, and 2. peripheral (venous) blood.
There is a common belief that hunger occurs when the blood glucose falls below the normal level. Well, this is NOT TRUE. I repeatedly tested my sugar level (using a glucometer) at a time when – after a hyperglycemic meal – I began to feel “animal hunger”. It always appeared in the area of 130-120 mg/dL.
My morning glycemia (just after waking up and before breakfast) is ~ 86 mg/dL and then I’m not hungry.
That is why when we are very hungry, we most often choose hyperglycemic meals. We feel subconsciously that sweets will satisfy our hunger the quickest. And so it is indeed: after the sweets, the concentration of glucose in the portal vein grows very rapidly, so the center of satiety is very quickly and rapidly stimulated.
However, this has its price: after hyperglycemic meals – the glucose decrease is equally rapid. This means that in an hour or two after a sweet feast, we will always feel a powerful hunger. And if – by some miracle – we manage to survive without a candy bar, in addition hypoglycemia appears, which doubles the alarm pulses sent to the center of hunger. (And then – if we feel jittery and our hands are trembling – this may indicate the beginning of diabetes). Our malaise lasts until the glucagon raises the blood glucose level. Most often, however, we do not let him do it..
Here it is time to return to my “Fatty Thursdays” and the fact that two hours after the 14th donut – I started hunting for meat. Now we know why.
If – during this hunger – we reach for sweets, they will quickly raise the level of glucose (and thus insulin). And everything will start again.
As a result, serving high-glycemic meals every 2-3 hours, we provoke the pancreas to secrete hectoliters of insulin, and – suffering from hunger every 2 hours – we gain weight.
And now a different situation:
Low Glycemic Meal
Instead of visiting the confectionery, we got up earlier and ate a low glycemic breakfast: wholemeal toasted * bread ** with chickpea hummus and fresh tomato slices.
*) Toasting bread before eating “additionally” lowers its glycemic index (GI).
**) It’s best to bake bread yourself – of course from wholemeal flour, bran and grains. (We will write about it in the section of culinary recipes).
Only then you can be sure that it does not contain E-something stabilizers and improvers – not to mention preservatives in the form of powdered COW’S HORNS or powdered PIG’S BRISTLES. I do not know how about you, but such uncertainty deprives me of my appetite.
After this breakfast, the glucose curve in blood takes on a mild shape; there is no rapid change in insulin levels, so no reactive hypoglycemia will occur.
It also means that we will not be hungry, even though after two hours the glucose level has approached the level of the norm. Insulin disappears from the blood, and glucagon replaces it, so we start to draw energy from our own ‘energy bank’ (our adipose tissue).
In summary: 2 hours after a low glycemic meal:
1. We are not hungry!
and at the same time:
2. We lose weight.
If this situation continues throughout the day, i.e. our other meals are also low glycemic – we are not hungry all day long.
And here, be aware of the important issue:
The fact that low glycemic meals elevate blood glucose very gently causes the center of satiety to be stimulated a little later – after a quarter of an hour. * We must remember this, especially when we eat rarely (2-3 meals a day).
*) Personally, I call it “devilish quarter”.
To defeat “devilish quarter” I tested 4 different methods:
- The Monk’s Method.
After each meal, repeat a prayer in your mind: “I will stop being hungry after a devilish quarter”. The method does not work. Mostly I was so absorbed in praying that I did not notice that – while praying – I was still eating.
- The Monk’s Method.
- “Eat & Runaway” Method
A short walk after each meal. In theory, the walk should help us survive until the hunger disappears. The method does not work. I never managed to go for a walk after a meal more than once.
- “Eat & Runaway” Method
- The Multi-Meals Method
Eat smaller meals 5-6 times a day. In theory – you always eat before you start to be hungry. The method works, but not for all people. One of my patients said about it: I know I should eat 6 times a day. And so I do, but… I can not resist eating between meals.
- The Multi-Meals Method
- The Turtle’s Method
It seems the best: Eat slowly, delighting every bite.
This method really works!
Especially in good company.
- The Turtle’s Method
What is a Glycemic Index (GI)
Let’s start with the reference pattern.
Imagine that the healthiest man in the world is eating pure glucose. After absorption, there will be a certain increase in blood glucose, which will stimulate the pancreas to release insulin.
This special and unique case: the IMPACT of PURE GLUCOSE on HEALTHY MAN’S BLOOD – we arbitrarily consider as a perfect model (that we will refer to) and arbitrarily set its value to 100.
Now imagine that we eat plain white bread.
It turns out that the increase in blood glucose caused by eating white bread * – it was only 70% of our pattern, which refers to eating pure glucose
*) we examine the effect on glycemia during the whole period of carbohydrate absorption, so up to ~ 2 hours after a meal
But how did we measure that it was just 70%?
We measure it like this:
First, we determine the glycemic curve of a specific food product.
Now, on this curve, we build a triangle and calculate its surface.
Finally, we compare it with the reference surface (for pure glucose) and multiply it by 100.
The value we get in this way is called the Glycemic Index – GI.
That is why we say that the Glycemic Index (GI) of glucose is 100 and GI of white bread is 70.
If we analyze other food products in the same way, we come to similar conclusions, eg GI of wholemeal bread (full milling) with bran and seeds = 40, but GI of burger bun = 95, etc.
Thus, the Glycemic Index is nothing but a comparison of:
- glycemia caused by a given product
in relation to
- glycemia caused by pure glucose.
In fact, GI can be determined for all food products. If they were complex products, their global GI would be hard to predict resultant (depending on all its components).
Glycemic energy load
Now it’s time to face the problem that Michel Montignac avoided, thanks to which his method is so liked by the adepts of his slimming method. However, for those who use this method, it is unfortunately something that causes the greatest havoc in the results of their efforts.
For a brief explanation:
The Michel Montignac method is a weight loss method based on Glycemic Index measurements. The basis of this method is to ensure that all your meals are low glycemic, thanks to which your pancreas does not release much insulin. The task of insulin is to store energy (as adipose tissue), so Montignac assumed that the lower the glycemic index (GI) of meals – the smaller the fat storage.
The MM method postulates the division of meals into two types:
– Carbohydrate Meal – 2 x daily (carbohydrates GI < 50 + protein)
– Fatty meal – 1 x a day (carbohydrates GI < 35 + protein + fats)
The principle is simple: if we eat fats, next to them on the plate we can only put carbohydrates with GI less than 35, because carbohydrates with a higher index would build this fat into our hips; if we do not eat fats (and only for example dairy products with less than 3% fat content), we put carbohydrates with IG < 50 on the plate.
The MM method has many disadvantages. I have already mentioned one of them in the article “Fat loss diet plan”: What is the point of prohibiting combining fats and carbohydrates on one plate, if fat appears in the blood 4 hours after glucose?
And since I am correcting Montignac, I will also add a few words about the substitute for sucrose, which he recommended – that is, fructose.
Here is a quote from a publication of the Warsaw Institute of Food and Nutrition:
“Unlike glucose, fructose enters the body’s cells without insulin. Therefore, the metabolism of fructose is more conducive to lipogenesis than glucose.”
So fructose breaks into adipose tissue – without invitation – and eagerly proceeds to the production of TG (by the way displaces some glucose from cells, which is responsible for a small GI of fructose).
So, be warned: If you intend to add pure fructose to your meals – do it carefully.
Currently, it is believed that high-fructose corn syrup (HFCS), used in the US food industry is the main cause of the obesity epidemic there.
I will admit immediately that I defended myself for a long time before accepting this cruel truth (I am talking about old times, when I was still a supporter of the MM method).
Thanks to MM I lost a lot of weight, however, it happened that my weight often stopped at some level (even for a month or longer). Sometimes, even – still using the MM method – I gained weight by 2-3 kg. Why?
The main question is:
When I eat low-glycemic meals…
Can I really eat as much as I want?
Again, let’s recall the glycemic curve and what I wrote about it in the article “The basics of weight loss”: “it can be assumed that the level of insulin in the blood is proportional to the level of glucose.”
Well, this is a big simplification I needed for clarity. This sentence, however, is not entirely true. To understand why, let me quote here the words of prof. Jerzy Rogulski from the book “Clinical biochemistry and analytics”, from the chapter discussing the glucose tolerance test:
“The course of glycemic curves in healthy people is essentially identical after loading glucose at 50, 75 or 100 g”.
Houston, we have a problem..
Whether I eat 50g glucose or 100g, the curve will be basically the same?
So looking at my blood glucose triangle, even Montignac himself would not guess how much glucose I ate?
This means that the glycemic curve is rather an indicator of the quality (assimilability) of carbohydrates contained in the diet, rather than their quantity.
Well, what happened to those extra 50g of glucose that does not change the appearance of the curve? Did I not absorb it into the blood? It passed through me unnoticed?
Well, no. I absorbed it, but you can not see it either on the glycemic curve or on the glycemic triangle based on it. And it will not be visible until we treat the glucose triangle as a flat cake. Meanwhile:
Unfortunately, all indications are that the glucose triangle – like a piece of pizza – also has its thickness. (I do not like it either, but it just has to be). And even more I do not like the fact that the thinner the triangle, the better. (Yes, we have a pizza-like problem here).
The course of the glycemic curve gives us only knowledge about the concentration of glucose in the blood at a given point in time. It does not say anything about the dynamics of the glucose removal process.
Meanwhile, to be aware of the actual glycemic energy load of the meal, we must also take into account the dynamics of glucose absorption.
If I put one bite of pizza in my mouth, I will swallow it and immediately put in my mouth the next bite of pizza, which I will swallow to immediately put another bite, etc., then in my mouth the concentration of pizza will always be equal to 1 bite.
If I now put in and swallow twice as fast, the concentration of the pizza in my mouth will not rise to 2 bites. I always have only 1 bite in my mouth, despite the fact that it is twice as quickly threshed by me.
Similarly with the concentration of glucose; if it is simultaneously 1. twice as quickly absorbed into the blood and 2. twice as quickly removed from it to the tissues – its concentration in the blood will not increase.
We must remember that we are not really concerned about glucose levels, but about insulin levels.
Returning to the example from the picture above: we need twice as much insulin to get rid of 100g of glucose from blood than to get rid of 50g. (At the same time, 2 times more insulin worked – to deal with a 2 times thicker glycemic triangle.)
So insulin had to be released, although the glycemic curve (in healthy people) remained blind.
For those who insist that insulin levels are always proportional to blood glucose levels, I have a question: where does reactive hypoglycemia come from? After a hyperglycemic meal, when the glucose level approaches normal – there is still insulin in the blood. This is the only explanation of reactive hypoglycemia.
So let’s not confuse the sugar curve with the insulin curve.
And here I will annoy everyone who loves Montignac for letting them not worry about the amount of calories consumed:
What was the meaning of calculating the surface area of the glycemic triangle? Was not it about estimating the amount of glucose absorbed and the amount of insulin released?
Meanwhile, since the triangle looks the same after eating different amounts of glucose, what gives us knowledge about its surface? Well, nothing.
And this is the main mistake of the Montignac method – the essence of his theory.
The efficiency of a healthy pancreas in removing glucose is at least 2 times higher than the result of the sugar curve.
Let’s not delude that it will be different with low-glycemic meals.
If we consume them in huge portions, despite the low blood glucose we will stop losing weight (because the triangles of low glycemic meals are also thinner or thicker).
The term “glycemic load” was created precisely for these reasons: it was found that large low glycemic meals give the same effect globally in the amount of secreted insulin, as high-glycemic meals of much lower mass.
Do not use a low glycemic diet!
Sooner or later you will start eating low glycemic index foods that have a huge energy load! And not even because you want to, but because your body – subconsciously – will start choosing such low-glycemic meals.
An extreme case would be an example of eating a cube of butter, which GI = 0. This is a slight exaggeration of course, but a nut-chocolate cream jar – also has an incredibly low GI – check if you do not believe it.
You should not be on any diet!
You should CHANGE YOUR EATING HABITS.
And the most healthy way of eating in the world is Whole Food Plant Based Nutrition – which is confirmed by the latest news from the world of science.
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If so, it just means he became a vegan a week or a month ago. Wait a year and look at him again.
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And look in the mirror next year.
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