Fast vs. Slow Carbohydrates: What Is the Difference -What Are The Best Types17 min estimated reading time

fast carbohydrates slow carbohydrates

Fast vs. Slow Carbohydrates: What Is the Difference – What Are The Best Types


In the food world, there are always two camps. You have the group that hates fats. On the other hand, is the group who hate carbohydrates. But it is not that simple. You have healthy products and unhealthy products from both categories.

For example, on the one hand, you have a chocolate cookie that consists mainly of carbohydrates and sugars. On the other hand, you have an apple, which consists mainly of carbohydrates and sugars. Yet you know that an apple is healthier than a chocolate cookie. What that difference causes you will learn in this article.

In addition, in this article you will learn:

  • What carbohydrates are and what they are made of
  • How carbohydrates are absorbed into the human body
  • What is the difference between fast and slow carbohydrates
  • Factors that influence the intake rate of a carbohydrate
  • What are the best carbohydrate sources

What Are Carbohydrates?

Nutrition is complex.


Once you think you know something about nutrition, there is still a lot of information behind that you literally give up the same minute.

And I will not blame you. But to show you a little bit about the world of nutrition, I will try to explain it to you in an understandable way. So let’s start.

Carbohydrates are seen as a macronutrient. Also, proteins and fats are seen as macronutrients. These 3 forms of fuel must ensure that our body remains alive.

This used to be quite a job. In prehistoric times, people had to ensure that enough food was available for an entire tribe. The main task of the men was hunting and the main task of women was to pick and find food and take care of the offspring.

Today, of course, this is very different. Are you hungry? Then you take a sprint to the supermarket and buy the first product that you like. And for that sprint is also something to say since it is exchanged for the car. But I digress …

A Long Chain of Sugars

We, therefore, need carbohydrates to stay alive, just like proteins and fats. These three nutrients cannot be created by our own body and must, therefore, be ingested via food.

A carbohydrate is made up of a long chain of sugars. That means that bread, potatoes, rice and pasta are mainly composed of long sugar chains. Sugars consist of one or more monosaccharides.

There are three main monosaccharides:

  • Glucose (grape sugar)
  • Fructose (fruit sugar)
  • Galactose

When sugar molecules bind together with many thousands, a carbohydrate is formed. Think of it as a long train where train wagons are the sugar molecules. The long chains of glucose are also called starch.

And you know starch from:

  • Potatoes
  • Bread
  • Pasta

Grains, legumes and vegetables are naturally starch. In sugars and dairy products, sugars occur naturally. The sugars in fruit are called fructose and the sugars in dairy products are called lactose (a combination of galactose and glucose).

What Makes Carbohydrates Special?

Carbohydrates are seen as the primary fuel for our body. Only then are proteins and fats addressed.

They are called first when energy is needed.

Carbohydrates are broken down into sugars and then stored in the body or immediately used as energy. In particular, the brain runs well on sugars. But in principle, they are used for all physical processes.

Only when your body runs through the carbohydrates does it start to use other energy sources such as proteins and fats. Ideally, you do not have your body to use proteins as an energy source, as these are also used for the recovery and maintenance of muscle cells. Fats, on the other hand, is a source of energy that everyone wants to use – the stored fats – that is, they ensure a lower fat percentage. Unfortunately, the waste process is not that simple.

How Are Carbohydrates Digested?

The absorption of nutrients takes place in the intestines. Then these nutrients are absorbed into the blood. If it is monosaccharides such as grape sugar, this can be done almost immediately. But more complex sugars such as starch must first be broken down into a few sugars.

This goes as follows:

  1. As soon as you take a bite of a piece of bread, the digestive enzymes in your mouth start working. They cut long sugar chains into pieces until a few sugars remain.
  2. Then the sugars are transported via the stomach to your intestines where the absorption can start from the blood.
  3. About one and a half hours after a carbohydrate-rich meal, sugar molecules all float in the blood. These sugar molecules must then be absorbed by your body cells so that they can be converted into energy. But this is not without a struggle.
  4. The body must first release insulin to the blood. Insulin causes the ports to open to the body cells so that the sugar molecules can be transported to the cells. Here the sugars can then be converted into energy and used.

Up to now, the carbohydrates do not seem to differ very much from each other, but this is certainly the case.

What brings me right to the next point:

Fast and Slow Carbohydrates

Above you could already read that grape sugar does not have to be broken down by digestive enzymes first and can, therefore, be absorbed very easily by the body. Most people think this is an advantage, but the opposite is true.

You prefer to eat carbohydrates that are slowly absorbed by the body. These are also called slow carbohydrates.

Why Are Fast Carbohydrates Unhealthy?

Fast carbohydrates are absorbed into the bloodstream from the intestines without any problems. This creates a very high blood sugar peak very quickly.

And you guessed what is needed for this:

  • A lot of insulin

Your body has to work almost overtime to process the sugars. High blood sugar is not good for the small blood vessels where they can cause damage. Out of fear your body releases a lot of insulin to the bloodstream, in the hope that the sugars can be transported quickly to your body cells.glucose-to-fat

When there is a lot of insulin in the blood, this is a sign for your body that a lot of energy is available. Then the signal is given to store these sugars as fat if they can not be used immediately.

This was very useful in prehistoric times. If there were harsh times with little food, then that can make the difference between surviving or not. You have stored extra fat which can later serve as fuel again. But in the present time, this is what makes for overweight. We no longer know those harsh times (fortunately) nowadays.

You not only will get fat from it, but it also spoils your health.

When large peaks in your blood sugar levels often occur and a lot of insulin needs to be released, this will not only affect brain-and-addictionsyour weight, but also your insulin sensitivity.

Your cells become less sensitive to insulin if there is a constant amount of insulin in the blood. You can compare it with eating sweet products.

In the past, strawberries were found to be sweet because little sweet food was available. Nowadays sugar is sprinkled on the strawberries because strawberry is not sweet enough.

That comes purely because our food has become sweeter over the years and your taste buds have become accustomed to it.

  • You, therefore, need more and more sugar to match the sweet taste.

Exactly the same applies to insulin. You need more and more insulin to absorb the sugars. This process is also called habituation.

When you become insulin-insensitive, the sugars cannot be absorbed from the blood, making your blood sugar too high. This can cause all kinds of diseases in the long term such as:Fast vs. Slow Carbohydrates

  • Diabetes type 2 (source)
  • High blood pressure (source)
  • Cardiovascular diseases (source)
  • Alzheimer’s disease (also called diabetes type 3) (source)
  • Cancer (source)

Fast carbohydrates make you fat and sick. But how can you know if a carbohydrate is healthy or unhealthy? you learn that in the following chapters.

What determines whether a carbohydrate is absorbed quickly or slowly?

There are certain properties of products that make them healthy or unhealthy. These points are so important that they make a product worth it to eat or to stand. Below you will find some features that ensure this.

The type of sugars

Not all sugars are the same. Many people only know sugar and think that all sorts of sugar are absorbed by the body. But you are wrong.

Fructose is a sugar that is absorbed more slowly by the body than, for example, glucose.

You would think that fructose is much healthier, but that is unfortunately not the case in this story.

Fructose is a sugar that is added to many products. You can not get around it nowadays. It is in almost every processed product. But fructose is also in fruit. You would think that it is not as unhealthy as you might think.

But from an evolutionary point of view, we have not known large amounts of fructose. Fructose could only be found in fruit and then also in small quantities. Fruit is grown very sweet nowadays so that there is more fructose in it than it used to be.

Actually, it is an unknown sugar for our body. That is also the reason why our body can not properly use this sugar and that a large part of it is converted into fat by your liver and then stored.

This perpetrator murders more people in the long term than any imaginable murderous dictator on earth.foods-with-high-fructose

Fructose in fruit is, fortunately, no problem. Fruit basically contains small quantities when compared with processed products, which are full of added sugar (fructose). Therefore, try to avoid as many processed products as possible. These are generally also fast carbohydrates.

The amount of fiber

This is one of the most important characteristics to determine whether a product is healthy or not. He is so important that if you only remember this property, I am already a happy man.

The amount of fiber in carbohydrate-rich products says something about the absorption rate of the carbohydrates. There are two different types of fibers and have their own properties.

Soluble fibers

The more fibers in a product, the slower the carbohydrates are absorbed into the bloodstream. The fibers that have this effect, in particular, are the soluble fibers. These fibers dissolve, as the word says, in water and can be further processed by your healthy intestinal bacteria. Then there is a gel-like mixture that envelops the nutrients of the meal. Similarly the sugars.fiber-and-blood sugar diagram

This gel-like mixture ensures that the sugars can be absorbed more difficult. For this reason, your blood sugar levels will have fewer peaks and valleys (source).

Because the sugars are absorbed more slowly, the sugars can also be used more gradually as an energy source. As a result, the chance that the sugars are stored as fat is also smaller.

This is, of course, useful for everyone, but especially type 2 diabetes patients can benefit from this. The fewer peaks they have in their blood sugar level, the more effective their body reacts to insulin. This reduces the burden on the pancreas. And also from the research showed that the more fibers they ate, the better their blood sugar was (source).

Insoluble fiber

But not only soluble fibers have advantages. Insoluble fibers can also take on a hero role. Despite the fact that they can only absorb moisture, they ensure that the food slush increases in volume so that you are saturated for a longer time and the feeling of hunger also comes back less quickly (source).

Fibers are covered by micronutrients because you do not need them to survive. And yet they provide much better health in the long run. They certainly deserve a place in “the hall of fame”.


Image result for eco diet banner

Preparation method

The method of preparation of a specific product can ensure that the carbohydrates are absorbed faster or more slowly.

As an example, I can best use a potato here.

Potatoes you can:

  • Cook
  • Frying
  • Baking
  • Cold by using a salad

When you fry potatoes and make fries out of them, the carbohydrates are absorbed faster in the bloodstream than when you only cook the potatoes.

Now I must honestly say that both ways cause a big blood sugar peak. Fries are only slightly more unhealthy than boiled potatoes.resistant-starch

There is one way in which potatoes become slightly healthier. That is when you eat them cold. And I do not mean that you have to eat raw potatoes, although that would be much healthier. But then I’m afraid you’re at the dentist tomorrow.

No, you have to cook them first and then put them in the fridge overnight.

When you let the potatoes cool overnight, the structure of some of the sugars in the potatoes changes. These are no longer digestible after a while and then behave like a fiber. They cannot be broken down and come out on the other side undigested. This is also called “resistant starch” (source).

This is the only way in which the carbohydrates in potatoes are absorbed more slowly and cause a lower blood sugar peak (source).

Ripening of a fruit

Unripe fruit contains more complex carbohydrates that break down into sugars as the fruit ripens.

Let me explain it simpler.

Which banana tastes sweeter?

  • A banana that you just bought and that is not yet ripe (green)?
  •  Or a banana that has been in the cupboard for a few days and that is already more mature (yellow/brown)?bananas from green to yellow/brown

You should opt for option two if all goes well.

An unripe banana contains more difficult to digest carbohydrates than a ripe banana. This makes your body more difficult to digest an unripe banana than with a ripe banana. The sugars from an unripe banana are therefore absorbed more slowly by the body (source).

Body response

This is something you, unfortunately, can not do much about.

Everybody reacts differently to carbohydrates. As a result, the absorption rate of carbohydrates is different for everybody.

One can eat anything that is loose and stuck, while the other already gains weight when he or she has been on holiday for three days and has eaten unhealthily. And the same applies to the processing of carbohydrates.

How quickly your blood sugar level rises from a certain product can be different for everyone. Despite this, you can, of course, take it into account. If you know that you are reacting badly to certain carbohydrates, the chances are that you store sugar faster. Then you are also the one who has to eat especially slow carbohydrates to stay healthy and slim.

Glycemic index and charge

To make things even more difficult, they devised a term for the absorption speed of carbohydrates and sugars, called:

The glycemic index

The glycemic index is a number between 0 and 100, which expresses the rate of the increase in blood sugar levels. Here, a value of 100 represents a very rapid increase and a value of, for example, a slow rise and a low peak again.


In fact, it is a very simple value to indicate whether a carbohydrate-rich source is healthy or unhealthy. The foods are compared with the absorption rate of 50 grams of pure glucose, which is used as a reference and has a glycemic value of 100.

  • Fast carbohydrates, therefore, have a high glycemic index
  •  Slow carbohydrates have a low glycemic index

“Very nice Tommy, but what is a low and high glycemic index?”

Officially, a glycemic index of under 55 is considered low, a value between 56 and 69 is considered average and a value above 70 is considered high.

Best Types Of Carbohydrates

Now we have reached the main point of this article. Because which products now contain mainly slow carbohydrates? Above I have already given a tip of the veil by saying that slow carbohydrates are mainly in unprocessed products. You can read more about these healthy products below.


There are many health gurus who disagree about many things in the food world. Actually to get tired of.vegetables-for-the-heart

But there is one thing that everyone agrees on. And that is that vegetables are healthy to eat.

Vegetables generally contain few carbohydrates and a lot of fiber. And these two actually also ensure that the carbohydrates are slowly absorbed and cause a low blood sugar peak.

You can literally eat as many vegetables as you want. Most people already have trouble with 300 grams. So you eat too little rather than too many vegetables.

Vegetables are extremely healthy for the body and that comes alongside the fibers:

  • Vitamins
  • Minerals
  • Antioxidants
  • Fiber

For example, all vegetables have anti-cancer properties due to the above nutrients (source, source).

There are vegetables that contain a little more carbohydrates. These are mainly vegetables that grow under the ground such as:

  • Potatoes, yes, these are officially also vegetables
  • Sweet potato
  • Carrots
  • Beetroot

You should not eat this vegetable too often as they contain a lot of starch. To prevent your blood sugar from rising so much, it is advisable to eat less of these vegetables and eat less often.


Fruit is a food group that is also full of healthy nutrients.

Not very different from vegetables also contains fruit:

  • Vitamins
  • Minerals
  • Antioxidants
  • Fiber

And the fibers in this food group also ensure a slow absorption of the fruit sugars. And most fruits also contain few sugars so you can eat a fair amount of them.

But here too there are exceptions such as:

  • Bananas
  • Grapes
  • Papaya
  • Pumpkin

All the above fruits contain a reasonable amount of sugar. Grapes and bananas also contain little fiber, which makes them less healthy for your blood sugar. These also automatically have a high glycemic index.


Many people find it difficult to leave their potatoes, rice or pasta during dinner. They are products that you are brought up with and that are the highlight of the meal.

And yet I do not recommend these products because of their great influence on your blood sugar level. But luckily you can replace them with legumes.

What makes legumes healthier than other starch products?

Legumes are a good source of:

  • Vitamins
  • Minerals
  • Fiber
  • Egg whites

That in contrast to potatoes, pasta and rice. The difference is mainly in the fibers. Legumes contain more fiber so that the glycemic index of this food group is lower than that of the other starch products.

For example, kidney beans have a glycemic index of 24, while boiled potatoes have a glycemic index of 78 (source). And let me not even start talking about mashed potatoes or fried potatoes. These are even higher.


Nuts are also unprocessed and you can find exactly in this form in nature.

Nuts are particularly known for their high calorific value. They contain a lot of calories because they also contain a lot of fats.

And yet they are one of the healthiest products to eat. Nuts have many health benefits (source).

What is most important to remember when selecting nuts is the ratio of omega-3 / omega-6 fatty acids.

Omega-3 fatty acids are namely anti-inflammatory fatty acids (source). For that reason, they are healthy for your body. Do you want to know more about the benefits of omega-3 fatty acids? Then read the articles below:

They are even so healthy (and safe) that no upper limit has been established for taking/eating omega-3 fatty acids.

Whole Grains Cereals

Do you belong to the group that can not say goodbye to cereal and starch products?

Then there might be a compromise that you can close so you can eat these products.

The wholemeal variant is many times healthier. These contain many more dietary fibers than non-wholemeal products. And here again, when more fibers are present, the sugars are absorbed more slowly and thus cause a lower blood sugar peak.

But beware: Despite the fact that products are whole grain, they still have a higher glycemic index than many other unprocessed products. Often the glycemic index is above 50, making it a high value. So try to eat these products as a minimum.

Below are some wholemeal products and their glycemic index:

Whole grain pasta                            48
Whole grain bread                            74
Brown rice                                         50
Oatmeal                                             55

Did you know that research shows that 1 in 3 just gains from a diet instead of losing weight? (source)

Metabolic cooking

Discover how you lose several kilos per week with tasty and easy to make slimming recipes!

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