Ketosis: Definition & Explanations

Ketose: Definition & Erklärungen

Ketosis is certainly not a familiar term for everyone. However, if you are planning to lose weight, ketosis can be a great help when it comes to losing weight and you might want to familiarize yourself with this term.

Because it is precisely in the area of ​​weight loss that so-called ketogenic diets are becoming more and more popular. But what exactly is ketosis or a ketogenic diet and how does it affect our body?

With this glossary entry we would like to answer these questions for you. We want to bring you closer to what exactly is behind the word ketosis. We also want to show you the advantages and disadvantages of ketosis. Have fun while reading.

the essentials in brief

  • Ketosis is a natural metabolism that can be triggered due to a lack of carbohydrates.
  • Ketosis can be diagnosed with a urine or blood test. Both test methods can be purchased at the pharmacy without difficulty.
  • The state of ketosis should not last forever. Because your body needs breaks from time to time to recover from the state of ketosis.

Glossary entry: The term ketosis explained in detail

Here we explain what exactly ketosis is and how it works in your body. We will also show you the advantages and disadvantages of ketosis.

What is ketosis?

Ketosis is a metabolic state in our body that causes an increased formation of ketone bodies, such as acetone, in our blood. These ketone bodies are alternative sources of energy derived from healthy fatty acids.

Have a good meal

Eggs are a very important food on a ketogenic diet. They bring the substance choline with them, which primarily has a cell-protecting function. (Source: Jasmin Schreiber/ unsplash)

Our body falls back on this alternative energy supply if it does not get enough glucose in the form of carbohydrates within 24 to 72 hours.

Glucose is, so to speak, our body's primary source of energy.

Therefore, ketosis is also referred to as starvation metabolism. This is how the body prepares itself for starvation and only obtains its energy from human fat storage, its second energy supplier.

What happens in the body when ketosis begins?

Different processes take place in your body when it switches from burning sugar to burning fat.

Once your body switches to burning fat, enzymes begin breaking down fat molecules in the liver. Fatty acids are converted into ketones, which your body can then use for fuel. The reduction in carbohydrate intake also has an effect on your blood sugar level.

At that time, ketosis was mainly used in times of famine and is a natural metabolism in response to bad times.

The onset of ketosis may also have some health benefits. However, we will only explain these to you in a later section. However, getting into ketosis can be very difficult for some people because our normal diet is very high in carbohydrates.

Even if you are already in ketosis, this does not mean that your body has adapted to ketosis.

The process of adapting to the new metabolism can be different for each person. On the one hand, he can adapt without any discomfort or flu-like symptoms occur during the body's adaptation phase to ketosis.

The symptoms of "feeling sick" usually last until the fat burning process in the body is running efficiently.

How do I get into ketosis?

The best way to put your body into ketosis is with a “ketogenic diet” or a targeted, long-term fast.

A "ketogenic diet" is a modification of a low-carb diet. It is characterized by the fact that it is particularly low in calories and sugar. In return, it is very high in fat.

If you plan to follow a ketogenic diet, you should avoid pasta, bread and rice in particular. Instead, fish, meat, eggs, and low-carb vegetables should be on a menu. Low-carb vegetables include:

  • avocados
  • zucchini
  • spinach
  • Mushrooms
  • broccoli

Another way to get into ketosis is intermittent fasting. In this form of fasting, food is avoided in a controlled manner for days or hours.

How quickly does ketosis kick in?

How quickly ketosis kicks in depends on your body's metabolic flexibility. It can therefore take from one to several days for it to set in.

Bakery products

To best support your metabolic transition, you should get rid of all processed foods and foods that contain carbohydrates, including bread, from your fridge. (Source: Rhett Noonan /unsplash)

Typically, most people get into ketosis after 5 days. This is because due to the reduction in carbohydrates, glycogen stores in the body slowly decrease.

What are the pros and cons of ketosis?

Ketosis can come with both some advantages and disadvantages. In this section we want to bring you closer to its advantages and disadvantages.

Benefits of Ketosis

The benefits of being in ketosis can include:

  • Rapid Weight Loss : This occurs through the depletion of glycogen that is initiated by reducing carbohydrate intake. Because for every gram of glycogen that the body stores, it stores 3 grams of water. As the diet begins, glycogen stores are depleted and the associated water is eliminated.(1)
  • Less feeling of hunger: This is due to the high percentage of fat that the body absorbs from a ketogenic diet. The fat in the main meals of the day leads to an increased feeling of satiety, even without carbohydrates. (2)
  • Stability of blood sugar . The blood sugar fluctuates constantly due to the intake of carbohydrates. However, since only little or no carbohydrates are supplied through food, the blood sugar remains stable throughout the day. This is because hardly any carbohydrates are burned and formed in the liver. Insulin is therefore only required in small amounts.(3)
  • Increased Endurance: This is because energy production from ketones and fatty acids does not require as much oxygen as energy production from glucose. This in turn leads to increased stamina.(4)
  • Boosting memory function : Another positive effect of ketosis is improved memory function. According to some studies, the ketogenic diet is said to improve both memory and concentration in a person.(5)
  • Improved sleep quality : A ketogenic diet can also have a positive impact on your sleep quality. If you are in the early stages, you may experience insomnia. However, this is again only due to the change that your body has to get used to. Once this phase is over, a ketogenic diet can significantly improve your deep sleep phase and make you feel more rested.(6)

Disadvantages of ketosis

Along with the benefits it brings, ketosis can also cause some side effects if not used properly. Since you should also know about the disadvantages of ketosis, we have presented some side effects here:

Especially at the beginning of a ketogenic diet, hypoglycaemia can occur in our body. In addition, diarrhea, vomiting or refusal to eat can occur, especially in relation to fasting. The main reason for this is the reduced intake of fiber, which can lead to such digestive problems.

If you have a fatty liver or a heart problem, you should also avoid a ketogenic diet. This is because the liver can be taxed by the high-fat foods used in the diet.

Since fruit is very high in sugar and is therefore avoided in a ketogenic diet, a vitamin or mineral deficiency can often occur. You should therefore make sure that you can cover your vitamin requirements elsewhere.

In addition, as has already been described in the section above, the ketogenic diet can have flu-like side effects. These include severe tiredness, lack of energy, difficulty concentrating and a reduced energy level.

Always talk to your doctor before starting a ketogenic diet. This is for your own health.

However, these should be overcome after the first 2 weeks of ketosis. If not, we recommend that you consult a doctor and, if necessary, pause the ketogenic diet for the time being.

How can I measure ketosis?

The easiest way to diagnose ketosis is with a urine or blood test, both of which you can get at a pharmacy.

You can use the urine test to determine if you are in ketosis or not, as our bodies flush out many ketogenic bodies in the first few weeks of the ketogenic diet.

However, if you want to measure your exact ketone levels, you should use a blood test. A small prick of the finger is enough to get a drop of blood. You can then use a ketone meter to measure your ketone levels using a test strip.

Here we have put together a small table of meaningful ketone values ​​for you.

ketone value Meaning
0.5mmol/L no ketosis
0.5 - 1.5 mmol/l Beginning of ketosis
1.5 - 3mmol/l In the midst of ketosis
3mmol/L Ketosis , but no weight loss benefits

At a value of 0.5 mmol/l you are not yet in ketosis. If the measured value is between 0.5 and 1.5 mmol/l, you are in the initial phase of ketosis. The value for losing weight is optimal if it is between 1.5 and 3 mmol/l. However, make sure that your value does not rise above 3 mmol/l. From this value, there is no rapid weight loss.

How long should you stay in ketosis

Your body shouldn't stay in ketosis forever. Ideal are 6-8 weeks, which your body can spend in ketosis without any problems. After that, you should start consuming carbohydrates from healthy sources such as berries. If you plan to continue in ketosis, it's best to give your body a break from ketosis for at least 2 weeks.

However, there are also some indicators that your body will give you if you have been in ketosis for too long.

Here we have compiled a short list of symptoms for you:

  1. Sleep: You don't feel as refreshed as you used to after a decent amount of sleep.
  2. Cravings: you are more hungry than usual despite following the diet correctly.
  3. Your weight is stagnant.
  4. Your ketone levels keep falling. This is often an indicator that your body needs a break from the diet.

Since ketosis was primarily intended to get our body through famine well, you should be careful not to stay in ketosis for too long.


Ketosis can be a useful tool for weight loss. Of course, this is only the case if you do ketosis properly and only for a certain amount of time. Especially in the first few weeks of adjusting your metabolism, your body can experience flu-like adjustment symptoms.

However, they are also short-lived. At this point, however, it is particularly important that you eat a balanced diet despite reducing carbohydrates. Consume enough fat as your body now gets its energy from it and drink enough so that there are no negative effects on you and your body.


  1. Effects of a low-carbohydrate diet on weight loss and cardiovascular risk factor in overweight adolescents; Stephen B. Sondike MD, Nancy Copperman MS, RD Marc S. Jacobson MD Society for Adolescent Medicine Annual Meeting, March 27, 2000.
  2. Gibson AA, Seimon RV, Lee CM, et al. Do ketogenic diets really suppress appetite? A systematic review and meta-analysis. Above Rev. 2015;16(1):64-76. doi:10.1111/obr.12230
  3. Yancy WS, Foy M, Chalecki AM et al. A low-carbohydrate, ketogenic diet to treat type 2 diabetes. Nutr Metab (Lond) 2, 34 (2005).
  4. Metabolic characteristics of keto-adapted ultra-endurance runners Jeff S Volek, Daniel J Freidenreich, Catherine Saenz, Laura J Kunces, Brent C Creighton, Jenna M Bartley, Patrick M Davitta, Colleen X Munoz, Jeffrey M Anderson, Carl M Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aernia, William J. Kraemer, Stephen D. Phinney
  5. Krikorian R, Shidler MD, Dangelo K, Couch SC, Benoit SC, Clegg DJ. Dietary ketosis enhances memory in mild cognitive impairment. Neurobiological Aging. 2012;33(2):425.e19-425.e4.25E27. doi:10.1016/j.neurobiolaging.2010.10.006
  6. Siegmann MJ, Athinarayanan SJ, Hallberg SJ, et al. Improvement in patient-reported sleep in type 2 diabetes and prediabetes participants receiving a continuous care intervention with nutritional ketosis. Sleep Med. 2019;55:92-99. doi:10.1016/j.sleep.2018.12.014
Back to blog
Vorheriger Beitrag

Nächster Beitrag

Leave a comment

Please note, comments need to be approved before they are published.