Insights
Squeezy Insights #1 – 120 g of carbs per hour and more—do you really need that?
29
July
July
Why I Believe Many Endurance Athletes Are Heading in the Wrong Direction Right Now.
Everyone is talking about 120 g of carbohydrates per hour and more. Hardly any other topic is currently being discussed as intensely in endurance sports as carbohydrate intake during exercise. In podcasts, professional athletes talk about consuming 120 g of carbohydrates per hour and even far more. On social media, people are debating which products are best suited for this. And in many training groups, the same question is now being asked: “Should I do this, too?” This is a perfectly valid question.
After all, if the world's best athletes consume such large amounts, it stands to reason that more carbohydrates automatically lead to better performance.
At this very point, however, I'd like to pause for a moment with you.
Not because high amounts of carbohydrates are inherently bad. Quite the contrary.
Under certain circumstances, they can even be crucial to performance. The real question, therefore, is not:
"How many carbohydrates can I eat?"
but rather:
"How many carbohydrates do I actually need?"
There is a crucial difference between these two questions.
And it is precisely this difference that often determines whether a dietary strategy makes sense—or whether one is simply trying to follow the latest trend.
Why I'm Writing This Article
For several decades now, I have been deeply involved in sports nutrition for endurance sports. During this time, I have witnessed many developments. Some have brought about lasting changes in the sport. Many others disappeared again after a short time.
In my view, the current discussion about ever-increasing amounts of carbohydrates is one of the most exciting developments of recent years. It also puts an end to the low-carb trend, and even the pathological consequences of chronic “underfueling,” such as RED-S syndrome, are pushed into the background as a result.
At the same time, however, I'm noticing something that is causing me increasing concern.
More and more athletes are basing their intake on the amounts consumed by professional athletes.
The problem here isn't just the number. The problem is the conclusion.
After all, people often get the impression that “if professionals consume 120 g or more per hour, I should aim for that, too.” This is exactly where many athletes unconsciously go down the wrong path.
And that's only because they overlook an important cause-and-effect relationship.
In most cases, high carbohydrate intake is not the cause of high performance. Rather, it is a consequence or result of exceptionally high performance. At first glance, this distinction may seem minor.
In fact, however, it changes the entire perspective on the topic of sports nutrition.
Let's start with a simple question
Imagine two cars: a compact car and a high-performance sports car.
Both drive the same route, but of course they take different amounts of time to do so. Do they use the same amount of fuel? Of course not. The sports car requires significantly more energy—not because its tank is larger, not because the driver is better at refueling, but because the engine produces more power and the vehicle is faster.
In humans, the principle is essentially the same: The greater the level of exertion, the higher the energy expenditure—and the higher the energy expenditure, the more energy must be supplied during prolonged exertion.
So far, this probably goes without saying.
Nevertheless, this very connection is often overlooked in the current discussion, as the focus is almost exclusively on carbohydrate intake.
Where does this energy come from?
During endurance exercise, your body essentially has two major sources of energy.
The first source is your fat metabolism—that is, your body fat.
The second source is your carbohydrate stores (glycogen stores in the liver and muscles) or the carbohydrates you consume during exercise.
Both systems usually operate simultaneously.
So there is no "switch" that toggles between fat and carbohydrate metabolism.
Rather, its share changes continuously based on performance.
Let's apply that to ourselves as athletes
Imagine two athletes. Both ride their bikes for 180 minutes at their individual moderate intensity levels. Both are on a flat course with the same wind conditions. One covers 75 km in three hours, while the other covers 120 km.
In this example, both consume 60 g of carbohydrates per hour.
This amount may be perfectly sufficient for one athlete, but significantly too little for another. Why?
Not because one person is in better shape. Not because their gastrointestinal tracts can process different amounts of food, but because both of them expend different amounts of energy during that hour—since higher performance always means a higher energy requirement. That is precisely the key point.
The amount of carbohydrates you need isn't based on some number that's currently being discussed online.
It is based on your individual energy needs and your performance level during exercise.
KHopt is better than KHmax
That is why I believe the term "KHopt" (carbohydrate optimum), which I would like to introduce here, is more helpful.
In recent years, much of the focus has been on the question: “How many grams of carbohydrates per hour can the gastrointestinal tract absorb (KHmax)?”
That is undoubtedly an interesting question, but it is not the most important one.
What's much more important is: How many carbohydrates do you need so that your body can maintain the required performance level over a certain period of time (KHopt)?
This is because anything significantly above that level does not automatically lead to further improvements in performance, but is often accompanied by gastrointestinal problems.
That is precisely what is often confused in the current discussion.
Another important point or variable
The higher the individual exercise intensity becomes, the more the body's energy supply shifts toward carbohydrates.
That doesn't mean that fat metabolism suddenly shuts down. It continues to function, but its role becomes less significant.
Carbohydrates are increasingly accounting for the larger share of energy supply. Therefore, carbohydrate requirements also increase during periods of very high exertion.
The actual order should therefore look like this:
First: How much energy do I personally need during exercise?
Second: What percentage of this energy does my body need to get from carbohydrates?
Third: Can my digestive system reliably absorb this amount?
In the current discussion, many people start at exactly the opposite end.
First, they ask, “How much can my gut absorb?”
Actually, this question should come last.
How is it even possible to consume large amounts of carbohydrates?
The answer leads us directly to glucose, fructose, and the various transport pathways in the intestine.
So far, we've been talking about the need.
Now let's take a look at how your body actually absorbs carbohydrates.
Don't worry, we're not going to dive deep into biochemistry right now.
But knowing a few basics goes a long way toward helping you better understand the current discussion.
Imagine your intestines as a train station.
After you eat or drink, carbohydrates first pass through your stomach into your small intestine. From there, they must be transported into the bloodstream. There are no “open doors” for this process. Instead, there are special “entrances” through which individual carbohydrates are absorbed. You can think of these entrances like train platforms. Not every train uses the same platform.
And that's exactly what makes the difference.
Glucose and fructose use different transport pathways.
Glucose is primarily absorbed via the SGLT1 transporter.
Fructose uses a different transporter, the GLUT5 transporter.
In theory, this has a major advantage.
If these two types of carbohydrates are combined effectively, both transport pathways can be utilized simultaneously. This means that, in theory, the body can absorb more carbohydrates overall than if only glucose were used.
That's why many modern sports drinks and energy gels today consist of a combination of different carbohydrate sources. Not because it sounds more modern.
But rather because, first and foremost, it makes physiological sense.
Does that automatically mean it should always contain glucose and fructose?
No, because people are different. While some athletes tolerate fructose just fine, others are much more sensitive to it. You might even have seen this in your own circle of friends and family.
Some athletes can easily consume several gels in a row.
The other person begins to experience a bloated stomach, a feeling of fullness, or gastrointestinal discomfort after just a short time.
The cause often isn't the carbohydrates themselves.
Rather, it depends on how well they can be accommodated on an individual basis.
A topic that is surprisingly rarely discussed
A significant portion of the population has a limited ability to absorb large amounts of fructose—a condition also known as fructose malabsorption (GLUT5 deficiency). It is generally accepted that 30–40% of all people in the Western Hemisphere have fructose malabsorption. These figures were not determined under load conditions!
During physical exertion in sports, this can affect as many as 50% of all athletes.
The severity can vary greatly.
That is why I think it is problematic to apply general recommendations to every athlete without first evaluating them.
Not everyone's metabolism works the same way. Not everyone's digestive system works the same way.
That's why there isn't one perfect carbohydrate strategy that works for everyone.
The key message, therefore, is not: Fructose—yes or no?
Instead: How does your own body react to it? How much fructose can it metabolize effectively relative to glucose?
Fixed ratios, such as 2:1 or 1:0.8, are nice marketing ideas, but in my opinion, they don't reflect the reality we athletes face.
No study can answer the question of what the right balance is.
It only responds to your own testing during training.
Another key factor for optimal carbohydrate intake
It never ceases to amaze me how many energy products—especially energy gels and energy drinks—are coming onto the market that completely ignore a crucial factor for optimal carbohydrate absorption.
Anyone who paid attention in school will surely remember the physical quantity known as osmolarity. It refers to the number of dissolved particles in an emulsion or a beverage. For us athletes, it’s important to know that the lower the osmolarity, the more easily and quickly our gastrointestinal tract can absorb the substance.
Therefore, we should avoid using ingredients that we do not absolutely need during exercise. The composition of the carbohydrates also plays a crucial role here. Glucose, for example, has a significantly higher osmolarity than maltodextrin (glucose polymers → glucose molecules linked together). For this reason, simple carbohydrate formulations made from pure glucose or fructose should generally be considered suboptimal.
That's why the gut is also part of your workout
Many athletes train their muscles. They train their cardiovascular system. They work on their technique. But they often forget about their gut.
In this process, the intestine can also adapt to recurring stress and a regular intake of carbohydrates (by developing SGLT1 and GLUT5 transporters).
That doesn't mean that every athlete can suddenly handle any amount.
However, it does mean that individual tolerance can often be improved. That is why gut training is now an integral part of modern sports nutrition for many professionals.
However—and this is important to me—only after it’s clear how much carbohydrate your body actually needs. Because then it will become clear whether gut training is even necessary for you. Not the other way around.
Five thoughts I'd like to share with you
- Mehr ist nicht automatisch besser.
Eine möglichst hohe Kohlenhydratzufuhr ist kein Selbstzweck.
Sie soll deine Leistung unterstützen – nicht einen neuen Rekord bei der Kohlenhydrataufnahme aufstellen. - Dein Energiebedarf bzw. deine Leistungsfähigkeit bestimmt deinen Kohlenhydratbedarf.
Nicht die Empfehlung eines Profis.
Nicht die Menge, die dein Trainingspartner verträgt.
Nicht der neueste Podcast.
Sondern deine individuelle Leistung während der Belastung. - Trainiere nicht nur deine Muskulatur.
Wenn dein Energiebedarf hohe Kohlenhydratmengen erforderlich macht, gehört auch dein Darm ins Training.
Denn auch er kann lernen, größere Mengen besser zu verarbeiten.
Aber erst dann, wenn diese Mengen überhaupt notwendig sind. - Höre auf deinen eigenen Körper.
Jeder Stoffwechsel ist anders.
Jeder Darm und damit auch die Menge an SGLT1- und GLUT5-Transportern ist individuell sehr unterschiedlich.
Deshalb ist Sporternährung immer auch ein großes Stück Individualität.
Es geht nicht darum, die Strategie eines anderen Athleten zu kopieren.
Es geht darum, die richtige Strategie für dich zu finden. - Understanding is more important than memorization.
Perhaps that is even the most important message of this article.
After all, if you understand why something works, you’ll be able to adapt your strategy to new developments later on or properly evaluate new recommendations.
Fewer marketing promises—more understanding.
—
Downloads
Preview of Part 2
In the next post, we'll take it a step further.
After all, if energy needs determine carbohydrate needs, this automatically raises the next intriguing question: How much energy can your body actually derive from fat metabolism—and when is fat alone no longer enough?
That is precisely where we begin to understand why some athletes need a lot of carbohydrates even at moderate intensities, while others benefit from fat metabolism for much longer.
And that is exactly where the answer to one of the most fascinating questions in modern sports nutrition begins