A ketogenic diet is one that is high in fat, moderate in protein, and low in carbohydrates; it seeks to mimic a state of fasting. The word "ketogenic" comes from the production of ketone bodies typical of fat metabolism, called acetoacetate, β-hydroxybutyrate, and acetone. These are responsible for supplying energy to the brain and heart on exceptional occasions, such as when following a diet with these characteristics.
In a standard ketogenic diet, the calorie supply is provided mainly by fats, followed by proteins, and in a minimal proportion by carbohydrates, which is totally opposite to the recommendations of a traditional diet, where nearly half of the calories are provided by the latter nutrient mentioned.
In a clinical setting, the ketogenic diet has been used as part of the treatment for some types of epilepsy, showing favorable results, according to several studies. However, in recent years, it has been attributed the ability to improve athletic performance—specifically in endurance sports—and has even been recommended for weight loss. It is important to clarify that if the purpose of the ketogenic diet is weight reduction, the caloric restriction must be around 500 calories per day, as is the case with other hypocaloric diets, so weight loss would be more associated with the total caloric deficit than the source of food being consumed.
In the ketogenic diet, there are no prohibited or permitted foods as such; in this diet, the most important thing is to know how to identify the food sources of fats, proteins, and carbohydrates, to know the permitted portions of each of these foods during meals throughout the day, and to recognize the appropriate portion sizes in order to meet the percentages proposed at the beginning of the treatment.
What should be taken into account if you wish to implement a ketogenic diet?
- This should be planned by a nutritionist, since the distribution of nutrients, especially the types of fats, must be carefully planned to avoid altering the lipid profile and thus risking cardiovascular health.
- It is possible that adhering to a ketogenic meal plan is not so simple, given the high restriction on carbohydrate consumption.
- It is possible that while following this type of diet, deficiencies in fiber and micronutrients such as water-soluble vitamins and some minerals may occur, so supplementation of these may be necessary, always under medical supervision.
- According to studies conducted to date, it is not a recommended diet for people with underlying liver or cardiovascular diseases, as their condition could worsen.
- Some of the adverse effects that could occur if this type of diet is followed are: constipation, halitosis, diarrhea, asthenia (feeling of lack of energy), and cramps.
- According to some studies, if a ketogenic diet is followed, it is possible that there may be a deterioration in some cognitive functions, such as: attention span, memory speed, rapid visual information processing, and information processing.
- It is recommended that the duration of a ketogenic diet should range between a minimum of 2 to 3 weeks and a maximum of 6-12 months. Except for some specific cases of epilepsy, a ketogenic diet should not be maintained for longer than 1 year, and in any case, it must be done under the supervision of a nutritionist.
- For cases of epilepsy, the prescription of the ketogenic diet must be made under the indication of the treating neurologist.
- Ketogenic diets do not offer significantly greater weight loss than conventional diets, so their use would not be as recommended and would not offer valuable benefits compared to the traditional diet. Being overweight is not sufficient reason to prescribe this type of diet.
Camila Henao Uribe
Nutritionist Dietitian
University of Antioquia