The ketogenic diet: what’s behind this nutritional plan?

Ketogene Diät: was steckt hinter der Ernährungsform?

The ketogenic diet exploits fat instead of carbohydrates for energy production, imitating the metabolic state that fasting produces in the body, a process known as ketosis. It is used effectively for medical treatment, but also as a diet for weight loss or muscle building.


The keto diet is low-carb and high-fat, which means that it largely dispenses with the sugar obtained from carbohydrates. If the body is not supplied with carbohydrates, the liver switches to fat and creates a glucose substitute, known as ketone bodies. These ketone bodies thus replace glucose as a supplier of energy.

Looking at the share of fat and carbohydrates, the distribution of nutrients deviates significantly from the recommendations given by the Swiss Society for Nutrition SGE. The protein content, however, remains almost the same because too much protein can interfere with ketosis.      

Keto Diet vs. SGE Recommendation: Comparison Distribution of Carbohydrates, Fats & Protein

Origine of the ketogenic diet

Often known today as a diet or as a method very popular among athletes for muscle building, the origin of this nutritional plan lies in medicine. The ketogenic diet was developed in the 1920s and has been used successfully ever since in treating severe epilepsy in children and adolescents. Studies show that a ketogenic diet reduces the frequency of seizures.      

Which foods are allowed, which are forbidden?

Fat is part of every meal, so treats like cheese fondue and bacon are not forbidden in this diet, but actually required. With an energy requirement of 2,000 kcal, a person’s daily intake should comprise165g fat, 40g carbohydrates and 75g protein. As a guideline: one portion of rice provides 40g of carbohydrates

Allowed are:

  • Vegetable oils like coconut oil and olive oil
  • Green, low-carb vegetables like spinach, lettuce, courgettes, cucumbers, celery, green beans
  • Avocado
  • Any kind of meat and processed foods like bacon
  • Dairy products like cheese, cream, butter
  • Nuts, seeds, nut butter
  • Eggs
  • Fish and shellfish, especially salmon, trout, mackerel

These foods are off the table

  • Cereal products such as bread, pasta, muesli, oats, rice
  • Pulses such as kidney beans, lentils and chickpeas
  • Potatoes and root vegetables like carrots, beetroot, parsnips
  • Sugar from sweets, cakes, biscuits, soft drinks, fruit juices
  • Sugar-rich fresh fruits like bananas, pineapple, grapes, mango and dried fruits

Disadvantages of the keto diet

  • Overall, however, the range of foods is extremely limited, which makes it very difficult to keep up in the long run and to avoid the yo-yo effect. The restrictions can also result in a lack of vitamins, minerals and fibre.
  • Not all fat is good fat, so food quality should be given the highest priority. Clear guidelines are lacking, which is why some people on the diet consume trans fats from deep-fried foods and many saturated fatty acids, yet it is precisely these that are associated with cardiovascular diseases. So anyone wishing to try out a ketogenic diet should include lots of polyunsaturated fatty acids in their menu plan.
  • All in all, a diet rich in fat and protein can also put a strain on the liver and kidneys in the long term.
  • The side effects of a ketogenic diet are fatigue, and in some cases the so-called keto flu. Sufferers experience tiredness, irritability, headaches, muscle cramps and possibly digestive problems. As with the flu, the symptoms should be short-lived and disappear after a few days or weeks.  

Advantages of the keto diet

The biggest advantage of a keto diet is that sugar is forbidden. This leads to quick weight-loss results. Particularly popular is a keto diet as a 3 to 6-month eating plan to kick-start a sustainable change of diet. After the 2 to 3-week adjustment phase, many people report feeling less hungry and also stronger and more energetic.


Due to the diet’s positive effect on epilepsy, recent research has also investigated its effect on cancer, diabetes, polycystic ovarian syndrome PCOS and Alzheimer's disease. Some studies demonstrate welcome results on epileptic seizures, for example. Whether the ketogenic diet works in the long term, which diseases it can help and whether it might even be harmful to health therefore remain controversial.

Not a balanced eating plan

Even if going without sugar has positive results – when following a ketogenic diet, the body is missing out on certain valuable vegetables and fruits. Pulses, fruit, pseudo-grains and other key sources of fibre, for example, don't form part of the plan. But experts say that these foods are particularly important for healthy digestion.


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