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Keto Diet: How It Works

by Josephine Andrews
Published: Last Updated on 357 views

The ketogenic diet , or keto diet for short , is a diet in which carbohydrates are almost completely avoided. This is intended to force the body to draw the energy it needs from the fat deposits. The extremely low-sugar diet is also used in tumor and epilepsy therapy. Read everything you need to know about the keto diet here.

What is a keto diet?

The keto diet is a low-carb diet – a maximum of five percent of the daily food intake consists of carbohydrates. This form of nutrition is based on the assumption that carbohydrates , not fat , make you fat . One of the most well-known representatives of the catabolic diet is the Atkins diet.

A ketogenic diet consists mainly of fat and protein. By not eating grain, fruit and vegetables, the body has no “fast” sources of energy available. This is supposed to get him to generate the sugar needed for the brain and other organs from the fat reserves. This process is called ketosis.

Ketosis was also pivotal in the origin of the diet . It was originally conceived in 1921 as a treatment for neurological disorders such as epilepsy. It turns out that patients had fewer epileptic seizures during the diet due to ketosis.

The keto diet is also used in cancer and tumor therapy. The basis is the theory that tumor cells can hardly utilize fatty acids. With the ketogenic diet, the tumor is supposed to be starved.

Ketogenic diets can also help significantly lower blood sugar and insulin levels.

How to recognize ketosis

If the body gets more carbohydrates than it needs for energy production, it stores them as fat. In addition, insulin, which becomes active as a storage hormone for carbohydrate storage, inhibits fat burning.

In ketosis, the body uses fat for fuel instead of carbohydrates. This happens when carbohydrates are significantly reduced in the diet and the supply of sugar (glucose) is restricted as a result. As a result, fat is converted into so-called ketone bodies in the liver. The body gets energy from them. So there is a change from carbohydrate metabolism to fat metabolism.

Blood, urine and breath tests help to determine ketosis. From a value of 0.5 millimol (mmol) / liter there is talk of a slight ketosis. A value between 2 and 5 mmol/liter is called ketosis.

Certain physical symptoms can also indicate ketosis. This includes:

  • increased thirst
  • dry mouth
  • frequent urination
  • decreased hunger or appetite

How does the keto diet work?

To achieve ketosis, you can only consume a maximum of 30 grams of carbohydrates per day, which corresponds to about 40 grams of pasta. The recommendation of the German Nutrition Society (DGE) for daily carbohydrate intake as part of a balanced diet is well over 200 grams for an adult – with a daily calorie intake of around 2000 calories. The ketogenic diet is very low in carbohydrates.

For this, a lot of protein in the form of meat and eggs is eaten to prevent muscle breakdown. The fat intake is also drastically increased in order to signal to the body that it is constantly being replenished, so it does not have to store the fat.

A ratio of the energy sources of

  • 70 to 80 percent fat
  • 20 to 25 percent protein
  • maximum 5 percent carbohydrates

There is also a moderate keto diet variant, in which 70 percent of energy comes from fat, 10 percent from protein and 20 percent from carbohydrates. Here, 60 percent of the fat comes from medium-chain fatty acids (MCTs), which are said to create more ketone bodies per unit. They are found in palm and coconut fat, for example.

Ketogenic Diet: These foods are allowed

A ketogenic diet focuses primarily on vegetables and high-fat foods. It is important that you mainly consume the polyunsaturated fatty acids, which are found in fish, avocados or nuts, for example. Also make sure that you cook primarily with fresh, unprocessed and high-quality foods.

The foods you can eat on a keto diet include:

meat and sausage

Both red and white meat are allowed. In addition, processed products such as ham or Viennese are no problem. The only restriction: Sausage must not contain any added sugar or starch.

However, when following a ketogenic diet, keep in mind that too much meat is unhealthy. This is especially true for processed products. The German Society for Nutrition advises adults not to eat more than 300 to 600 grams of meat and sausages per week.

Here you can find out more about how much meat is healthy.

fish and seafood

Oily fish such as salmon, trout, tuna and mackerel are particularly suitable for a keto diet. Anchovies, cod or herring are also allowed.

You are also welcome to access seafood. They usually contain no or only a few carbohydrates, but valuable nutrients. The menu may therefore include:

  • shrimp
  • Hummer
  • Octopus
  • crayfish
  • Shrimps
  • scallops
  • caviar


Green vegetables and collards are the focus of a ketogenic diet. These include spinach, broccoli , cabbage, cauliflower, and kale. But that’s not all: Aubergine, mushrooms and zucchini are also allowed. You can also eat tomatoes, onions and peppers.

Be sure to avoid starchy vegetables. These include root vegetables like parsnips, carrots, and potatoes.


Fruit choices are severely limited on a keto diet. Only berries and the stone fruit varieties avocado and olives are allowed.

dairy products and eggs

When it comes to cheese, you can access unprocessed varieties such as cheddar, blue cheese or mozzarella. Parmesan, cottage cheese , Gouda, Brie, ricotta or mascarpone are also allowed. However, reduced-fat and light products are not suitable for a keto diet.

The following applies to other dairy products such as cream, butter , yoghurt or quark: choose types with a high fat content.

Eggs are also allowed on a keto diet. They contain only a small amount of carbohydrates and a lot of protein.

nuts and seeds

Nuts and seeds are an important source of energy for the body on a ketogenic diet. An important requirement is that they are natural. Get access to:

  • almonds
  • Cashewkerne
  • walnuts
  • Pecannüssen
  • pistachios
  • linseed
  • Chia seeds
  • pine nuts
  • sunflower seeds
  • pumpkin seeds

Healthy oils and fats

Medium-chain fats are particularly important in a ketogenic diet. Your advantage: They are converted directly by the body into ketone bodies and completely metabolized. Therefore use

  • extra virgin olive oil
  • Avocadoöl
  • walnut oil
  • coconut oil
  • Palm oil
  • cocoa butter
  • Nussmus


As for drinks, anything that doesn’t contain sugar is allowed. Specifically: water , unsweetened teas and coffee. Detox water with fruit or vegetable additives and unsweetened plant-based milk are also possible.

Find out more about detox water and plant -based milk here .

spices and sweeteners

The following applies to spices: If they are pure and unprocessed, there is nothing to be said against them. Refine your dishes with, among other things

For sweeteners, erythritol , stevia and xilit are allowed. But be careful: only use small amounts.

Ketogenic diet: These foods are forbidden

On a ketogenic diet, avoid all foods high in carbohydrates. This includes:

  • Grain products such as baked goods and pasta
  • Reis
  • Fruit (except berries, avocado, and olives)
  • Legumes such as lentils, chickpeas and beans
  • Root vegetables like potatoes, sweet potatoes, carrots, and parsnips
  • sugary drinks like sodas and fruit juices
  • sweets, cakes and ice cream
  • reduced-fat and light products
  • processed products such as sauces, mustard and ketchup
  • processed vegetable oils
  • Alcohol

That brings the keto diet

The keto diet has various effects on the body. On the one hand, it helps with weight loss , on the other hand, it also has health effects.

Lose weight with the ketogenic diet

The high protein content in a ketogenic diet fills you up faster and keeps you hungry for longer. In addition, the muscle mass is not lost. So weight loss is likely. Often people who stick to the keto diet report feeling better subjectively.

It was also shown that the diet drastically improves insulin sensitivity, which can have positive effects on metabolism. It should also help the body store less fat and burn more.

Some studies suggest that a ketogenic diet is more effective than a low-fat diet for weight loss. The prerequisite is that the participants consume the same amount of calories.

Health effects of the keto diet

There are studies that show that people on a keto diet have slightly better cholesterol levels than the general population, despite having periods of very high fat.

The ketogenic diet can also help improve risk factors like body fat, good HDL cholesterol, blood pressure, and blood sugar.

There are also the following notes:

  • It was shown that a keto diet could reduce epileptic seizures, especially in children.
  • The diet is currently being researched as an add-on treatment for cancer because it may help slow tumor growth.
  • The keto diet may help reduce the symptoms of Alzheimer’s disease and slow its progression. Ketone bodies appear to be a good source of energy for the brain.
  • According to a study, the keto diet also helps with Parkinson’s disease. However, further research is required.

Risks of the Keto Diet

The keto diet is not without its downsides. There is no nutrition plan with prescribed meals, but the high proportion of fat and protein can lead to indigestion, tiredness and even vomiting in the initial phase. In addition, many people who follow a ketogenic diet smell of acetone.

There is also a risk of ketoacidosis, i.e. acidification of the blood by ketone bodies. This can be life-threatening! The risk of cardiovascular disease also increases if you eat too much saturated fat. Because these usually also increase the cholesterol level.

The high-fat and protein-rich diet can also put a strain on the liver and kidneys. Inadequate intake of vitamins and minerals can lead to further deficiency symptoms.

A ketogenic diet also sometimes alters your body’s water and mineral balance. Therefore, it may help to add extra salt to your meals or take mineral supplements. Don’t do this on suspicion, but talk to your doctor or a nutritionist about it.

The ketogenic diet is very strict because, proponents theorize, even a single “day of sin” breaks ketosis and negates the effectiveness of the diet. However, it is precisely this propagated effectiveness that is difficult to prove scientifically. Reliable statements on the effectiveness are only made very cautiously.

Tips for everyday life

If you decide to go on a ketogenic diet, there are a few tips that can make it easier to incorporate into your daily routine.

  • Start with a moderate, low-carb diet so your body gets used to burning more fat.
  • Eat your fill, at least at the beginning, so that your body is not subjected to too much exertion and adjustments at once.
  • Plan your meals days in advance and cook for yourself as often as you can. If you are short on time during the week, you can prepare some dishes ahead of time and freeze them.
  • Bring your own food to the canteen or friends’ house to avoid disrupting ketosis.

Who is a ketogenic diet suitable for?

A ketogenic diet is suitable for people who:

  • are overweight
  • can benefit from it for health reasons (epilepsy, diabetes Alzheimer’s, Parkinson’s, cancer, etc.)

If you have kidney problems or other health problems, it is better to avoid it. Athletes should also be careful. The study situation on “low carb” nutrition does not show any clear advantages for performance. Rather, they are threatened by a nutrient deficiency with a ketogenic diet.

Since the ketogenic diet comes with some risks, it’s wise to talk to a nutritionist or healthcare professional first.

The ketogenic diet: conclusion

Many experts are particularly critical of the extremely low vitamin and extremely high fat and protein intake over a long period of time. Also: If you have kidney weakness or other health problems, you should keep your hands off the extreme amounts of fat and protein.

In summary, if you want to lose weight, you can do it in a healthier and more balanced way. Anyone who still wants to try the keto diet because they are overweight or as part of a therapy should only do so under medical supervision.


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