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?
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.
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.
The ketogenic diet deviates greatly from the nutrient distribution recommended by the Swiss Society for Nutrition, which suggests consuming the following breakdown:
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.
Most of the permitted foods are those with a high fat content:
Foods with high levels of carbohydrates are not permitted:
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The ketogenic diet has various effects that help you to lose weight:
It may sound promising, but the possible disadvantages of using the ketogenic diet for weight loss also have to be taken into account.
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.
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.
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.
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.
David Fäh lectures and conducts research at the Bern University of Applied Sciences, School of Health Professions, Specialist Area Nutrition and Dietetics. He provided the editorial team with advice and input for this article.