Ketosis – a different kind of metabolism: effective weight loss and healthier eating

The keto diet is widely discussed and often results not only in rapid and sustained weight loss, but also in improved concentration and enhanced physical performance. Our article explains what to consider during ketosis and which foods are permitted.

7 Min

Last updated on 29.12.2025

from Paulina

Contents

A positive body image and reaching one's ideal weight are extremely important to many people. It's no wonder that there are more and more diets, programs, and metabolism-boosting miracle cures on the market, often promising the moon. The so-called ketosis is also increasingly popular and sparks interest in many people wanting to try it out for themselves.

The keto diet is a sustainable method that helps with weight loss. But how exactly does it work in our bodies? And what does the associated ketogenic diet look like?

The ketogenic metabolic process under scrutiny

Now for a bit of theory: Biochemically speaking, ketosis means the metabolism of fats . Accordingly, fats are used as a starting material in the body and converted into so-called ketone bodies through various metabolic processes, thereby generating energy. Fat can also serve as an energy source – a property that surprises many people. Especially in the weight-loss industry, fat is often strongly demonized, yet fats are just as important for our bodies as carbohydrates and proteins.

The human body typically obtains energy from carbohydrates by converting them into ATP (adenosine triphosphate). However, if carbohydrates are unavailable for an extended period, it turns to fats and converts them into energy. This process is called ketosis, during which the body's fat reserves are depleted. Through ketogenesis in the liver, fats and proteins are converted into other substances in a series of metabolic steps. The breakdown of fatty acids produces a coenzyme called acetyl-CoA. From this, ketone bodies are produced, which then serve as the body's energy source.

Normally, ketosis is an emergency state for the body , serving to provide energy even during times of scarcity. However, you can also consciously and intentionally induce ketosis by following a ketogenic diet. This diet is based on healthy fats and proteins, with carbohydrates essentially eliminated from the menu. The lack of carbohydrates, in turn, causes the body to switch its energy metabolism and metabolize fats . This metabolic state is also known as "starvation mode."

Ketone bodies: Definition & explanation

The ketone bodies produced during ketogenesis serve as an energy source and are "burned" to generate energy that is essential for the brain and muscles. Acetone, acetoacetate, and beta-hydroxybutyrate (BHB) are typically produced in this process. This is also much more efficient than energy production from carbohydrates , as a ketone body can be converted into energy in only three to five steps. The conversion of glucose requires 26 steps.

What's special about ketone bodies is that they are water-soluble and therefore quickly transported via our bloodstream and can also cross the blood-brain barrier. This means they can be absorbed and used much more quickly by the brain, as well as the heart, kidneys, muscles, and other energy-demanding organs.

How ketosis works

If you decide to follow a ketogenic diet, it is of course helpful to know exactly how it works, what needs to be considered during the transition, and how long the transition actually takes.

The transition itself can take anywhere from one to several days , although this is only a rough guideline, as everyone reacts individually. A prerequisite for this is that the body has depleted all its glucose stores and is forced to use fat as an energy source. But how exactly does keto work?

Our bodies change their metabolism as soon as they no longer have carbohydrates available. Accordingly, carbohydrate consumption is reduced to a minimum . The ratio of macronutrients is very important in this process. We have provided a rough guideline below:

70% fat
20% protein
10% carbohydrates

According to this, your diet should consist of 70% fat, 20% protein, and 10% carbohydrates . However, it's important to know that even 10% carbohydrates can sometimes be too much. Therefore, it's quite possible that this value needs to be reduced further (to around 5%) for the body to enter ketosis.

How many grams result from this ratio?

Assuming a daily requirement of 2000 kcal, the individual amounts can be calculated precisely:

1 g of fat corresponds to 9 kcal
1 g of protein corresponds to 4 kcal
1 g of carbohydrates corresponds to 4 kcal

The basic formula for the calculation is:

The individual calorie requirement x the percentage of the respective macronutrient
________________________________________
Number of calories per 1 g of macronutrient

This results in the following values:

Fat: 2000 x 0.7 / 9 = 156 g
Protein: 2000 x 0.2 / 4 = 100g
Carbohydrates: 2000 x 0.1 / 4 = 50g

How you know you're in ketosis

The simplest way is to measure the ketone levels in the body . Various tests are available on the market for this purpose. Urine tests in the form of ketone strips are particularly popular. However, breathalyzers and blood tests are also available.

Otherwise, it also depends on your own perception. A prolonged feeling of fullness after eating is a key indicator, as is a reduced appetite and the absence of cravings. A sweetish breath is also a sign of ketone bodies and thus ketosis in the body.

Benefits of ketosis

A ketogenic diet offers several advantages, which is why it is very popular, especially for weight loss, but also for improving performance. The following benefits are significant for many people:

Improved and more effective fat burning

Logically, fat metabolism offers much more efficient fat burning in the body than other diets. This allows you to lose weight quickly and sustainably , and maintain that weight loss. The ketone bodies produced have a satiating effect and prevent cravings by lowering the hormones responsible for them in the body.

constant blood sugar level

During a ketogenic diet, blood sugar and insulin levels are said to stabilize significantly . This is because they no longer fluctuate due to the regular consumption and metabolism of carbohydrates.

Increased concentration skills

Improved concentration can be explained by the high water solubility of ketone bodies. They are not only metabolized more efficiently than carbohydrates, but are also an ideal energy source for our brain , as they can essentially cross the blood-brain barrier unimpeded, thus providing energy much more quickly. This, in turn, allows our brain to function faster and increases our concentration . Regular intake of healthy fats is also said to promote brain health, since the brain itself is composed of fats. Omega-3 fatty acids are particularly beneficial in this regard.

The body has more energy available.

The faster and more efficient metabolism of fats into ketone bodies provides our body with more energy . This means that not only the brain, but also all other organs and muscles are adequately supplied with energy. As a result, we are more productive throughout the day and generally more focused.

Disadvantages of the ketogenic diet

In addition to the advantages, the disadvantages shouldn't be overlooked. Above all, strict adherence is crucial and can sometimes be very difficult, because as soon as the body has carbohydrates available, it immediately switches to the simpler metabolic process. You should also expect circulatory problems, digestive issues, or headaches and stomach aches , especially at the beginning of the dietary change . This is due to the reduced blood sugar levels. It's sometimes called the "low-carb flu." However, once the transition is complete, these symptoms quickly subside.

Choosing the right foods isn't always easy and requires a lot of creativity. However, once you get the hang of it, you'll develop an intuition for how much fat your body needs.

Notice

At this point it is very important to drink plenty of fluids and not to overexert yourself, so take frequent breaks!

Healthy or dangerous? An assessment of the ketogenic diet.

A ketogenic diet keeps you feeling full longer, boosts your physical performance, and has many other benefits. But is it really healthy? After all, from an evolutionary perspective, ketosis is more of an emergency survival mechanism.

Therefore , it is quite conceivable that people may have a negative reaction to ketosis.
Some people react to this diet and may not be able to maintain it long-term. In particular, the increased consumption of animal fats can put a strain on the kidneys, and the consumption of not only healthy fats but also saturated fatty acids and other unhealthy fats is often problematic. Furthermore, long-term studies are lacking to make definitive statements on this topic. In case of doubt, it is always advisable to consult a doctor.

Basic principles of the ketogenic diet

The most important thing is to reduce carbohydrate intake to a minimum. This means that only between 20 and 50 grams of carbohydrates should be eaten per day . Values between 20 and 30 grams are even better. However, it always depends on the individual's basal metabolic rate.

As soon as more fats are consumed, the body has to adjust by producing more enzymes that can break them down again. This naturally takes a few days.

A list of suitable foods for the keto diet

Proper nutrition is absolutely essential during this transition. This is especially true for the significantly higher fat intake, whereby the fats consumed must be "healthy" so that they can be metabolized effectively.

Healthy oils and fats

Fats are the primary energy source during ketosis and therefore make up the largest portion of this diet. The following foods are highly recommended:

Cold-pressed olive oil
coconut oil
Avocado oil
Butter from pasture-raised animals
Egg yolks from pasture-raised hens
Fish oil
Krill oil

Tip

When choosing oils, opt for high-quality organic options whenever possible. You should also avoid highly processed fats and oils, as well as margarine, sunflower oil, peanut oil, and animal fats from factory farming.

Important protein sources

Proteins are also important in this diet, but should not be consumed in excess, as they can otherwise be metabolized into carbohydrates in the body, thus ending ketosis. The following protein-rich foods are suitable:

Free-range eggs
Organic meat from pasture-raised animals
Wild-caught fish

Here you should avoid soy products, conventional protein powders, and also meat and fish from factory farms.

Relevant vegetable varieties

Of course, many vegetables are important sources of vitamins and fiber. However, you should also make sure that the vegetables you choose contain high-quality oils and fats. These vegetables are recommended:

broccoli
Cucumber
avocado
zucchini
arugula
Lamb's lettuce
radish
garlic and onions
Mushrooms
tomatoes
Olives
Cauliflower

At this point, you should avoid starchy and carbohydrate-rich foods such as pumpkin, potatoes, or sweet potatoes, as these cause the body to exit ketogenic metabolism and return to normal metabolism.

Seeds and nuts as important plant-based fat sources

Nuts are an important source of plant-based fats. However, they also contain a small amount of carbohydrates and antinutrients and should therefore be consumed in moderation. The following are suitable:

almonds
Walnuts
Pecan nuts
Pistachios
Chia seeds
Cashew nuts
Hazelnuts
Macadamia nuts

Berries and fruits

Fruits and berries are an important source of phytochemicals, vitamins, and minerals . However, they can contain fructose, which can inhibit ketosis. Therefore, it's best to choose low-fructose varieties . These include:

Strawberries
Blueberries
Lemons
limes
Raspberries
blackberries

drinks

Even your beverage choices should be carefully considered when following a ketogenic diet. Ideally, you should drink water, mineral water, unsweetened herbal teas, or homemade lemonades . Bone broth and Bulletproof Coffee in the morning are also common. Soft drinks, with or without sugar or artificial sweeteners, should be avoided at all costs. Alcoholic beverages such as beer, cocktails, and white wine are veritable carbohydrate bombs and should be strictly avoided.

Tip

If you do want to consume alcoholic beverages, you should opt for rum, vodka, or whiskey. Similar types are also fine as long as they are low in carbohydrates.

How to successfully change your diet

There are several ways to enter ketosis. Fasting, in particular, is a great help for many people to get started with this way of eating. Not only does intermittent fasting help, but even a 24-hour fast can be effective. Generally, after fasting, you should exclusively follow a ketogenic diet. You will also enter ketosis as soon as you keep your carbohydrate intake below 50g per day for at least 14 days and eat a high-fat diet.

However, it is very important not only to reduce carbohydrate intake but also to completely deplete the body's glucose stores . Only then will the body begin ketosis. Therefore, the process takes a few days and can sometimes be accelerated somewhat through endurance exercise.

A balanced diet and the quality of the food are particularly important in the ketogenic diet. Our Balance Shake and Fat Burner can also be helpful. Thanks to the guarana extract it contains, it supports fat burning.

Ketosis – a brief summary

Ketosis is a very popular diet that aids in weight loss and improved concentration. It involves "artificially" putting the body into a state of starvation by minimizing carbohydrate intake while drastically increasing fat consumption. This causes the body to use fat, rather than carbohydrates, as its primary energy source.

This is also the origin of the name "fat metabolism," because both ingested fats and the body's fat stores are used as energy sources and processed into ketone bodies. These ketone bodies are then transported via the bloodstream to organs, brain, and muscles, where they perform their function. However, this transition takes time and varies from person to person. Furthermore, the body can be quickly "kicked out" of ketosis as soon as there is even the slightest chance of consuming carbohydrates. Therefore, a consistent approach is crucial.

FAQ about ketosis

Still have questions about ketosis? Here we clarify the most important information about ketosis and the ketogenic diet:

What is ketosis?

Ketosis refers to the fat metabolism in the human body and occurs when the body no longer has carbohydrates or glucose available as an energy source. It is also called starvation metabolism and derives energy from both the body's fat stores and ingested fats. The original purpose of ketosis is therefore to keep the body alive and provide it with energy during times of scarcity. Today, however, ketosis is also frequently used for weight loss.

At what point are you in ketosis?

The transition can take one to several days. It's especially difficult for people who previously consumed a lot of carbohydrates to adjust. Generally, you can expect it to take five to seven days. However, even this is just a rough guideline.

How do you know you're in ketosis?

There are several signs of this, although headaches or even fatigue can certainly occur at the beginning of the dietary change. Specific indications that the body is in ketosis include:

Dry mouth despite ample fluid intake
weight loss
Measurement of ketone bodies in urine using any measurement methods
sweetish to pungent bad breath
Digestive problems
high concentration

When does one fall out of ketosis?

The body falls out of ketosis as soon as carbohydrates are available again in any form. This can happen through the consumption of carbohydrates or alcoholic beverages, or through excessive protein consumption, which can also be metabolized into carbohydrates through a process called gluconeogenesis, which in turn provides energy.

What role does exercise play in ketosis?

Endurance sports, in particular, can help accelerate the dietary change and thus bring the body into ketosis sooner. However, only aerobic sports such as swimming, cycling, or yoga are helpful in this regard. Light strength training using one's own body weight can also be beneficial.

¹ The approval process for these health-related claims is not yet complete.

Sources:

Bahr LS, Bellmann-Strobl J, Michalsen A. The ketogenic diet – what it can do, how it works and how to follow it successfully. zkm 20 https://www.thieme-connect.de/products/ejournals/pdf/10.1055/a-0584-5311.pdf
LMU University Hospital https://www.lmu-klinikum.de/aktuelles/newsmeldungen/einfluss-von-ketogener-diat-auf-das-immunsystem/5e8435e2daf58905
Good Clinical Practice Network https://ichgcp.net/de/clinical-trials-registry/NCT04492228
German Journal of Sports Medicine https://www.zeitschrift-sportmedizin.de/ketogene-ernaehrung-als-fitness-option/

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Ketosis – a different kind of metabolism: effective weight loss and healthier eating