All you need to know about your carbs

Published: 27th of May 2020 by – Last Update: 16th of April 2024

Alrighty! Let's talk about carbs.

Carbs, or carbohydrates, are one of the primary energy sources we feed on. No wonder carbohydrates build so much organic mass and are a highly available potential food source globally (and unlike animals, plants won't run away).

In this article, we will learn about carbohydrates, how they work and how we use them, what "good carbs" and "bad carbs" are, and finally, what carbs we should preferably eat.

It is all in your greens.

You won't find much carbs in animal products. If there's any, then only in traces. Carbohydrates are a product of photosynthesis, where plants transform sunlight's energy into a solid and energy-rich molecule. This molecule marks the entry point of life as we know it. Even if you look at bacteria, you find one type that does photosynthesis and one that depends on the energy supply produced.

The smallest type of this molecule is called a monosaccharide, but better known under the term sugar. There are several types of those sugars, but they all have their basic structure in common, which allows them to be combined into longer and more complex structures, the so-called polysaccharides.

The shorter and less complex carbs are dissoluble in water and quickly digestible. The more complex a carb is, the harder it tends to be broken down. Many structures become so complex and strong that we cannot digest them. In nutrition, you know them under the term fiber. Even though we cannot break down fiber, it is still meaningful in digestion, as it feeds microbiomes, carries out toxic substances, and moves the chymus in your guts forward.

Covering less than 10% of your total calories from sugar is recommended to sustain a healthy lifestyle. You should aim below 5% calories from sugar to enjoy more health benefits.

How we make use of glucose

The type of carb we make use of is a short sugar molecule called glucose. If we encounter this one during digestion, we can directly absorb and use it. If we encounter more complex ones, our body must invest time and energy to break down the big lump into small usable sugars. This process already starts in your mouth. If you chew a piece of bread for a couple of seconds, your saliva will start breaking down the carbs, and you will soon feel a sweet taste on your tongue.

Other simple sugars, like fructose or galactose, can be encountered. Unlike glucose, these sugars cannot be directly absorbed. They must be metabolized in the liver into glucose before they can enter the bloodstream as glucose or triglycerides (fat).

One gram of carbohydrates supplies 4 kcal of energy. You can consider that a "gross" value since our body must also actively break down more complex carbohydrates to use them as sugars.

During its journey through the digestive system, everything is broken down into sugars and finally picked up in the small intestine. The liver then releases it into the bloodstream.

When sugar enters your blood, your pancreas will release the hormone insulin, which allows the sugar to traverse cell walls and reach its final destination for energy production. Excess glucose can be transformed into fat and stored in your muffin tops.

Blood sugar levels

Sugar is a crucial energy source for our brain. We constantly have it in our bloodstream, and its levels are critical for our health. Too low blood sugar can lead to lowered brain functionality, seizures, and shock. If your body cannot handle blood sugar levels that are too high, excess glucose will be released through urine. Along with sugar, you lose a large amount of water. This can lead to dehydration and over-acidification. Under normal conditions, however, you can release enough insulin to use the glucose filtering through the kidneys.

The body tries to keep the blood sugar in a reasonable range. We need the glucose levels in our blood to ensure enough energy is accessible. Too high levels will be actively regulated by releasing more insulin into your blood. When dropping low, our brain will signal hunger. With the consumption of foods, our blood sugar levels then rise again.

Why there are "good carbs" and "bad carbs"

By now, we understand the basic mechanisms behind carb intake and blood sugar levels: The less complex a carb is, the faster it will be absorbed into the blood. The faster the concentration of sugar rises, the sooner it will be downregulated with insulin. All extra that we cannot put into fast storage will not be thrown out but saved in triglycerides.

There is no "smartness" behind this rule, like throttling the absorption when carbs are available. Whatever is available will end up in your blood instantly. Therefore, choosing the right carbs can keep you full over a longer period and prevent binge eating and frequent hunger attacks. Carbs that go slow on you are considered "good" carbs, while sugars that quickly spike and fall in your blood sugar levels are the bad boys.

When carbs gradually enter the bloodstream, you can benefit from two positive effects: Your blood sugar rise is less steep and keeps you full longer. Like this, your body does not need to release high amounts of insulin to prevent entering critical sugar levels. The slow absorption of more complex carbs allows you to stay full longer, even though the intake of the overall calories stays the same.

Bad carbs, on the other hand, enter quickly and make your body react fast. Your current need will be covered, but anything that goes on top of that must be regulated to prevent unhealthy blood sugar levels. Not only will you store the extra, but you will also enter low sugar levels again in no time. This signals more hunger and you have the urge to eat again.

Blood sugar response to different qualities of carbs
Try flattening THIS curve. It's easier than you think. Trust me!

Following this fast-paced rhythm based on fast sugars, you easily pile up more calories than you need. Instead, choose carbs that keep you running through the day. Slow and complex carbs are what you want. You will not only be full for longer, but high amounts of fiber will also help move unwanted substances from your body.

The scientific way of rating carbs

Luckily, science has us covered. There are two key indicators for rating carbs. First, we want to see how fast they get absorbed into our bloodstream, and second, we should know how dense our food is packed with carbs.

The glycaemic index represents the speed of absorption. What sounds complicated is a pretty straightforward measure: Let's say you eat food worth 50g of carbs and measure how high your blood sugar levels rise within 2 hours. The result relates to blood sugar levels from an intake of 50g of pure sugar.

A glycaemic index score of 100 means your blood sugar rises as fast as if you ate pure glucose. The lower the number, the slower the absorption, thus the longer you will feed on the carbs.

Many public databases cover whole and processed foods if you love numbers and want exact answers. The public searchable database from the University of Sydney, for example, is easily accessible and kept up to date.

The second side of the medal is the glycemic load. In non-nerd speak, this means how many digestible carbs are available in a fixed amount of food. The higher the load, the more carb-dense the food.

Again, if you like math, you can easily calculate the load. You multiply the glycemic index with the available calories from carbs per unit.

The glycaemic index describes how steeply the curve rises when looking at the curves above. When measuring the whole area under each graph, you look at the glycemic load. While both curves can draw an area of the same size, the index describes how well it is distributed over time. A less steep curve finally allows you to use your carbs longer.

Fast Carbs and Complex Carbs in Food

I guess you are not into checking numbers before each meal. Luckily, that's not even necessary. If you look at your plate, you can easily pick the right type of carbs.

Complex carbs serve as a building block for our plants, providing the necessary stability to grow high. Short sugars don't fulfill that purpose, especially since they are soluble in water and easily broken down into single sugars. You will find higher amounts of short carbs where their purpose is to serve energy, such as in seeds or fruit.

"High" amounts of complex carbs are no problem in natural food. It only turns ugly when food gets refined and processed, making single sugars more accessible. Take white flour as an example: the plain powder used in white bread has little to do with wheat in its original form.

While a grain contains a shell, skin layers, and a core, flour only consists of the core, broken down into tiny bits. The carbohydrates you find here are mainly starches, quickly broken down to sugar.

The same food can differ dramatically in absorption depending on how finely processed it is. This table shows the glycemic properties of wheat and wheat products. The degree of processing correlates with a rise in the glycemic index.

FoodGlycemic indexGlycemic load
White Bread, Wheat Flour7211
Turkish Bread, Whole Wheat498
Bulgur (a part of wheat)4612
Whole Wheat Kernels3011

Eating each of those provides roughly the same amount of calories. However, white bread makes you hungry again at more than double the speed of whole wheat kernels.

Is replacing glucose with fructose a better choice?

Fructose plays a distinct role in metabolism and has different impacts on the glycemic index (GI). 

Glucose is a primary energy source for the body's cells and is particularly vital for the brain and red blood cells. Upon consumption, glucose can be readily utilized in glycolysis, the metabolic pathway that breaks down carbohydrates to produce energy. This process occurs in nearly all cells, making glucose a universal fuel for the body.

Fructose follows a different metabolic pathway. Unlike glucose, fructose is almost exclusively metabolized in the liver, converting it into glucose, lactate, and fatty acids. This unique pathway means fructose has a lower GI than glucose, causing a lesser immediate rise in blood sugar levels

However, this does not necessarily make fructose a healthier alternative. The liver's processing of fructose produces triglycerides, which can contribute to fatty liver disease and insulin resistance, a precursor to type 2 diabetes.

Swapping glucose for fructose to manage blood sugar levels is not straightforward. While fructose has a lower GI, suggesting a minor impact on blood sugar, its metabolism in the liver and the subsequent effects on lipid production and insulin sensitivity must be considered.

High fructose intake can lead to metabolic disturbances, including increased visceral fat and uric acid levels, risk factors for heart disease and gout. Therefore, substituting glucose with fructose should be cautiously approached, considering the broader implications on metabolic health beyond the glycemic response.

But what about fruit?

Yes, yes! Fruit is sweet, and that's true in most cases. I understand your first reaction is avoiding fruit because of its high sweetness. The sugar in juice can indeed be absorbed directly. Still, I tell you that fruit is good for you!

Let's look at one extreme example to make it clear: watermelon! In terms of the glycaemic index, Watermelon competes with highly processed foods. Considering that watermelon mainly holds water, the glycaemic load is super low.

So, despite its sweet taste, watermelon won't give you much energy. To compensate for a meal of 500 kcal with just watermelon, you would need to eat about 1.6 kilos of watermelon—that's just not realistic.

berries are a healthy example of a low-GI food with only a minor impact from carbs.
Not just a safe option—Berries are generally super beneficial due to their supply of antioxidants and vitamins and low glycaemic load.

The quintessence is about the same for any fruit. Of course, there are variations in sweetness and calorie density, but overall, fruits won't wreck your diet, thanks to the low glycemic load. You need tons of it to kick yourself out of balance with just fruit.

Make smart choices instead of cutting carbs.

To get the most out of your carbs, you should ensure they keep you full for a long time. This can easily be achieved by eating fresh, unprocessed whole foods instead of regularly consuming highly processed food. When you manage to stay full for a longer time, you automatically will crave food less frequently.

You can start by making small changes in your shopping list — you don't need to cut calories to get more out of your carbs. Instead of buying plain white bread, go for the whole-grain version. This will keep you full for longer, and whole foods will benefit you with more micronutrients and fiber. The same applies to pasta, rice, and cereals.

Carbs applied to the Boston consulting matrix theory. It fits, but inverted.
Example foods for each group.

Try to pick the whole-food version of things like muesli, granola, etc. Food doesn't need to be coated in sugar to be tasty. You can easily add sweetness by chopping some fresh fruit.

I suggest you inspect one item on your shopping list at a time. Changing your whole habits at once tends to be extreme and can leave you happy and satisfied. Instead, try changing it bit by bit.

Look at your inventory and replace one item with a healthier option. If you are comfortable with your choice, keep it and move on to the next thing. This will steadily improve your supply without hopping from one extreme to the other.

Why processed foods are the bottleneck in our food chain

The basic rule for a healthy diet applies to carbs as well. Eat with variety, eat whole foods, and keep things balanced. Too often, the items offered on supermarket shelves break every rule.

A lot of industrial food does not focus on healthy benefits. Ultimately, shelf life, an addictive taste, and a competitive price are the main drivers for most decision-making. From a marketing perspective, the optimal food is food that sells fast, is cheap to produce, and hooks the customer. Nutritional value is a plus that gets printed as a highlight on the package.

No wonder — if texture, fat, and sugar can drive sales, it's clear to follow that pathway to keep your shareholders happy. And since most shoppers are price-sensitive, you need to cut quality to win the pitch on the shelf.

You see, we are after several decades of industrial food production. When shopping, we enter a jungle of choices presented in colorful boxes. Many of them claim this and that nutrient as a highlight and often try to trick you into thinking this is a healthy product. Making the right choice is hard if you don't look at the nutrients directly.

The best way out of that jungle again is not to rely on processed foods that much. I don't ask to cut everything that gets sold in a package. Many good foods are still packed, like pasta or rice. You should be more careful with packaged food that needs to maintain "freshness" for a while, like baked items such as pre-packed bread or crispy cookies. And even if you stay in that range, you often still got a choice and can look for a whole-grain low-sugar version of the same damn thing.

What you can learn from the nutrition label about carbs in the product

When you are new to nutrition and want to start learning about foods, you likely don't know which products you might want to pick yet. Examining the ingredients and nutrition labels can significantly help in this situation.

Generally, fresh and whole foods should be preferred. But when it comes to processed foods, it is worth taking a deeper look at the ingredients. No matter what product you look at, you can easily spot bad carbs and sugars, even in products you would not expect. It is important to know that most countries require the manufacturer to list them according to their predominance, ordered by the amount used.

If the first few ingredients on the list contain keywords like sugar, fructose, glucose, starch, or flour, expect them to be high in fast carbs. This is common for many baked items. It's worth having a look at the nutrition table. The overall carbs, excluding fiber, can be interpreted as the glycaemic load. The higher their proportion in a 100g serving, the more carbs you can expect.

Next, examine the sugars and compare them to the total carbohydrates. The more sugars in the total carbohydrates, the higher the food's glycemic index.

Following this simple rule can help you make your match easily. Baked goods, preferably made from whole grains, can contain high carbs and low sugars. In soups, sauces, and dressings, high carbs indicate added sugars, which you should avoid. You might even find them in meaty products.

A healthy muesli. now THIS is meal material.
Kellogg's coco pops as seen in their Australian Website, 2020
Per 100gMuesliCoco PopsCompared
Energy396 kcal392 kcal98%
Total Carbs78.04 g87.4 g111%
Sugars2.02 g32.4 g1603%
Fibre6.72 g1.7 g25%

Applying the lessons learned the right way.

If you start analyzing your food and looking at the nutrients, you will soon learn which items to pick, and which might be banished from your fridge. Don't focus on numbers, and don't be too picky with your choices. Sometimes, letting the heart win is just the right thing to do.

Overall, understanding your carbs is not that hard if you apply some common sense and follow the basic rules. If it's fresh and natural, it's good! Eat many of these regularly with a good variety, and you are on a good path. An exception here and there won't ruin anything, but ensure it stays the exception.

In a nutshell

Carbs are your main energy source; they are highly available and fast-acting. We get them mainly from plants. We can distinguish between short sugars like mono or disaccharide, more complex carbs, and dietary fiber.

The less complex a carb is, the faster it can raise blood sugar. Longer carbs, therefore, can keep you full longer and prevent frequent hunger attacks.

To find "good carbs," you should rely on whole foods. Processed foods often contain a high amount of "fast carbs," which get absorbed fast and leave you hungry again after a short while. You don't need to worry about bad carbs if you mainly rely on fresh and whole foods.

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