What are the pros and cons of the ketogenic diet?7 min estimated reading time

pros and cons of ketogenic diet

What are the pros and cons of the ketogenic diet?

Is the ketogenic diet an effective way for weight loss, sports performance or building muscle mass? 

Read the answer here!

More and more people are following a ketogenic diet. But is this really such a miracle diet?

What does it mean?

The ketogenic diet is a diet that mainly eats fats (80%) and low protein and carbohydrates (20%). The diet focuses on fat as a primary energy source. Normally the carbohydrates that are eaten are broken down into glucose, which ends up in the bloodstream, after which it is transported to the cells. With this diet, there is less glucose in the bloodstream because few carbohydrates are eaten.

The body does not get enough energy from the glucose for the basic functions. In response, the liver switches to breaking down fats, after which ketones enter the body. These ketones are then used as an energy source.

We speak of ketosis when the body uses fats as an energy source in the metabolic state.

In order to get the body into ketosis as quickly as possible, a ratio of 90% fats and 10% proteins and as few carbohydrates as possible can be chosen first. The only foods with carbohydrates that are eaten are green vegetables. Rice, bread, pasta and products with sugar are avoided. Bacon, eggs, nuts and fatty meat, on the other hand, are increased.

Different diets

  • Classic ketogenic diet: 80% consists of fats, 1 gram of proteins per kilo of body weight and the rest of the energy consists of carbohydrates. For someone of 60 kg with a daily energy requirement of 1800 kcal, this amounts to 160 grams of fat, 60 grams of protein and 30 grams of carbohydrates.
  • MCT ketogenic diet: MCT (medium-chain triglycerides) are fats that occur in palm and coconut oil. These fats differ from the LCT (long-chain fats) that are mainly found in animal products. The MCT ketogenic diet consists of 70% fats, 10% proteins and 20% carbohydrates. Because of the MCT fats, fewer fats are needed to get into ketosis. MCT fats are absorbed differently in the body. This allows more proteins and carbohydrates to be eaten.
  • Cyclic ketogenic diet: During the week is eaten according to the traditional ketogenic diet, at the weekend carbohydrates may be eaten. In this way, the stocks of glycogen in the muscles are stored again. Because of this, you will have less trouble during exercise. The strength is less, but not as bad as with the normal ketogenic diet. The first two weeks do eat according to the traditional diet to get into ketosis. Sport is played during the ketogenic days.
  • Targeted ketogenic diet: The difference with the cyclic ketogenic diet is that 25-50 grams of extra carbohydrates may be eaten on the days that you exercise. This is sufficient for average training but not for endurance sports at high intensity.

Ketogenic diet and lose weight

Many diets are based on the principle of a ketogenic or low-carbohydrate diet. For example, think of Atkins. In summary, it comes down to this:

A low carbohydrate diet in combination with a negative energy balance often leads to short-term weight loss. Losing weight is certainly possible with such a diet because you quickly achieve a negative energy balance by omitting many foods. Unfortunately, only a small group maintains this weight loss and almost everyone falls back after a few months. This is also apparent from scientific research that shows that 90% of people fall back on their old pattern. In short, a ketogenic diet does not seem to be the solution.

The figure below provides an overview of the pros and cons of a low-carbohydrate diet. This was chosen because the advantages and disadvantages are almost comparable.

Low-Carbohydrate Diet
Pros and Cons
Regular Food Pattern
Pros and Cons
Short term: a lot of weight lossBetter to maintain: No food products are excluded
Over a period of a few months, weight loss is hardly different with a healthy diet with an increased protein intakeA complete diet
Often difficult to sustainFewer people fall back to the old weight
Risks of malnutritionThe weight loss during the first few weeks is less fast than with a low-carbohydrate diet
Often no or little fat loss, but fluid loss

What is the difference between the ketogenic and low-carbohydrate diet?

Now, unlike the ketogenic diet, a low-carbohydrate diet eats more protein instead of fat. In this way, muscle mass is better preserved during the line period. However, recent research among 17 overweight adults that looked at the effect of the ketogenic diet on muscle mass shows that a ketogenic diet does not lead to more fat loss, but to more muscle loss than a fat restriction. Muscle mass increases the energy requirement, loss of this is not desirable and can lead to the so-called yo-yo effect. For that reason, I am not in favor of a ketogenic diet for weight loss.

The ketogenic diet and sport

In general, carbohydrates as an energy source are more effective for sports performance than fats. The reason for this is that the burning of carbohydrates requires less oxygen and therefore the energy supply runs faster. A small supply of carbohydrates in the muscles negatively influences heavy efforts. At the moment there is a lot of discussion about the effect of a Low Carb High Fat (LCHF) diet on sports performance. It would have a positive effect on ultra-endurance performance (longer than 2-3 hours) on low effort (<80% VO2max). However, researchers are still discussing this with each other. Looking at the performance and the current scientific consensus, I will not recommend this diet. And certainly not for the average athlete.

Epilepsy and the ketogenic diet

The ketogenic diet is basically not designed to lose weight. It was developed in the 1920s for people suffering from epilepsy. In 30% of people with epilepsy, medication does not work or does not work well enough. The ketogenic diet can then be an option. How this works exactly is still unknown, but the diet is primarily effective in children. This is probably because the brains of young children are in full development.

Because the ketogenic diet is quite strict, it is only used in children with a difficult-to-treat form of epilepsy. The child must be admitted for a few days and adjusted to the new diet by a dietician under the supervision of a nurse, neurologist and/or pediatrician. After admission, the diet is continued at home and the child remains under control. Within 3 months it is usually clear whether the diet has an effect. After 2 to 3 years the diet will in principle be phased out slowly.

The effects are striking:

  • 1 in 3 children experiences a 90% attack reduction or is even completely attack-free.
  • 1 in 3 children has a 50-90% reduction in seizures.
  • In 1 in 3 children, the diet has no effect on the attacks.
  • It is striking that many parents think that their child is more alert due to the diet and that behavior improves.

Side effects

The ketogenic diet can have several side effects.

Think about:

  • fatigue
  • feeling absent
  • hypoglycemia
  • poorly functioning bowel movements (low in fiber)
  • dietary deficiencies
  • kidney stones.

During the introduction of the ketogenic diet, the body must get used to using fats for energy. This can cause symptoms such as nausea, lightness in the head, tiredness, feeling weak, feeling cold, diarrhea and headache.

Ketosis is often confused with ketoacidosis; a dangerous state of the body where the acidity of the blood is too high. This form can occur with type 1 diabetes if there is a shortage of insulin.

This is hardly the case with healthy persons.


The ketogenic diet is a diet that mainly eats fats (80%) and low protein and carbohydrates (20%). This diet is aimed at allowing the body to use fats for energy instead of carbohydrates. In the short term, this diet can certainly help you lose weight quickly.

However, with prolonged use you will miss many nutrients, you will lose muscle mass, your performance will be negatively affected and a ketogenic diet will bring many other possible side effects. This diet is therefore not at all prepared to lose weight. It was developed in the 1920s for people with epilepsy. Here, especially with children, promising results can be seen. However, this diet must be used under the supervision of a specialized dietitian and neurologist.

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