Ketogenic diet: fad or fab?

A ketogenic diet is composed mainly of proteins and fats. Carbohydrates do not appear on the menu very often. This type of diet promises rapid weight loss, but does it actually work? And what are the benefits and disadvantages of the keto diet?

07.02.2022 Lara Brunner 4 minutes

The keto diet has its origins in the medical world. It was – and still is – used to minimise epileptic seizures in children and young people. Today, this diet is mostly popular among people who want to lose fat or weight.

How does the ketogenic diet work?

Low-carb and high-fat: the keto diet primarily involves reducing intake of carbohydrates. This causes the metabolism to enter into what is known as ketosis: the liver starts to break down fat instead of carbohydrates and produces a glucose substitute called ketone bodies. Normally, the body primarily uses glucose and fats for energy. In this case, the organs that normally use glucose use the ketone bodies instead.

Is a ketogenic diet a balanced diet?

The ketogenic diet deviates greatly from the nutrient distribution recommended by the Swiss Society for Nutrition, which suggests consuming the following breakdown:

  • Carbohydrates: 50%
  • Fat: 35%
  • Protein 15%

In a ketogenic diet, the percentage of energy that comes from proteins remains around the same (10 to 20%). You do, however, eat a lot more fat (70 to 80%) and greatly reduce your carbohydrate intake (5 to 10%). This means that if you consume 2,000 kcal per day, your intake of carbohydrates would be less than 50 g. Furthermore, many nutrient-rich vegetables and fruits are not on the menu.

Which foods are permitted in the ketogenic diet?

Most of the permitted foods are those with a high fat content:

  • Plant oils
  • Green vegetables low in carbohydrates, such as spinach, lettuce and broccoli
  • Fruits with less fructose, such as papaya and berries
  • Avocados
  • Meat
  • Fish and seafood
  • Low-sugar dairy products
  • Eggs
  • Nuts and seeds

Which foods are not permitted in the ketogenic diet?

Foods with high levels of carbohydrates are not permitted:

  • Grains
  • Pulses
  • Potatoes and root vegetables
  • Sweets
  • Fruits with high sugar content, such as bananas, grapes and dried fruits
  • Vegetables with a high sugar content, such as cooked carrots and radishes
  • Processed products with hidden sugar, such as yoghurt and some tinned food
  • Drinks with added or natural sugar, such as sweet drinks, fruit juice and milk
  • Sweeteners, such as Xylit
  • Natural sweeteners, such as honey and agave syrup

Do you have any questions about nutrition or your weight?

Our health consultation advisors are happy to help you. We can offer you information and tips on balanced nutrition and controlling your weight.

Is the ketogenic diet suitable for dieting?

The ketogenic diet has various effects that help you to lose weight:

  • As blood sugar fluctuates less, you are less likely to have cravings.
  • The body produces less appetite-stimulating hormones such as ghrelin. It also improves the effect of appetite-suppressing hormones, so we feel full faster.
  • When the body converts fat into ketone bodies, it uses more calories than under normal conditions.
  • As the insulin level is constantly low, the body breaks down more fat.
  • The ketone bodies have a hunger-reducing effect.

It may sound promising, but the possible disadvantages of using the ketogenic diet for weight loss also have to be taken into account.

  • Those who follow the ketogenic diet have to greatly minimise the type of food they eat. This results in restrictions that are not always easy to stick to. It can also lead to relapses and social withdrawal, among other things. The risk of an eating disorder has also not been conclusively researched yet.
  • At the beginning, the body breaks down a lot of muscle mass and loses weight in the form of glycogen (sugar reserves in the body) and water. This leads to quick results on the scales. However, the goal is to break down fat.
  • The ketogenic diet is not balanced. It leads to a reduced intake of fibre and some micronutrients, and could lead to dietary deficiencies.
  • The effect of an undersupply of carbohydrates has not yet been conclusively researched. It can lead to a reduction in physical and mental capabilities.
  • Furthermore, the effect of this diet is often not sustainable. After following the keto diet, the yo-yo effect can occur. This means that when you start eating as you did before the diet, the kilos you lost quickly pile back on again. If you want to maintain a healthy weight over the long term, you have to eat a balanced died and adjust your calorie intake to your individual calorie needs.
Tips for a balanced diet Everything you need to know about calories

Other health advantages of the ketogenic diet

In the short and medium term, this diet reduces certain risk factors for cardiovascular diseases and type 2 diabetes. Furthermore, in the short term, cognitive parameters such as the ability to concentrate can be improved in people both with and without dementia.

The ketogenic diet also has an anti-inflammatory effect, which can lead to improved complexion.

There is still too little scientific evidence on the other advantages, such as its effectiveness against cancer and non-alcoholic fatty liver disease.

Other health disadvantages of the ketogenic diet

A possible consequence of a fat-rich diet is deposits in the blood vessels and high cholesterol. In the long run, the ketogenic diet can also strain the liver and kidneys due to the increased intake of proteins and fats, which could lead to gall stones or kidney stones. Furthermore, it needs to be taken into account that not all fats are equally healthy. The body can process unsaturated fatty acids much better than saturated fatty acids.

Key facts about fat

Both before and during a pregnancy, the ketogenic diet also increases the risk of spina bifida and gestational diabetes. The former risk is increased even when enough folic acid is consumed.

And if this diet leads to nutrient deficiencies, osteoporosis, anaemia and neurological deficits are all possible consequences.

Side effects of the keto diet

Those who are tired and irritable, plagued by headaches and muscle cramps and have digestion problems are likely suffering from the “keto flu”. It is unpleasant, but not dangerous. These complaints arise because of the sudden reduction in carbohydrate intake – and therefore less glucose. The body has to first get used to this. Just like a normal flu, the symptoms should disappear on their own within a few days.


Losing weight through the ketogenic diet generally happens due to the huge reduction in the amount of calories consumed. However, you can also achieve this kind of weight loss by making sustainable changes to your diet. A strict ketogenic diet is not balanced and is very restrictive. Furthermore, it has not yet been possible to conclusively research what the health effects are of following this diet over a longer period of time. The studies contain too many deficiencies and are too short. This is why you should only start this diet in consultation with a doctor or a dietitian.

Read more

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