Introduction and objective:
The course of the aging process, among other things, depends on the lifestyle. Considering the influence of nutrition on the functioning of the body, it seems important to analyze the effects of using restrictive dietary models in this group, which have been very popular for years. The literature on the characteristics and side effects of the ketogenic diet (KD) was reviewed to assess the risks, associated with its restrictions, in the context of older people.

Review methods:
The literature review was performed using information from the PubMed and Google Scholar database.

Abbreviated description of the state of knowledge:
KD as a low-carbohydrate and high-fat diet leads to the formation of ketone bodies, which become an alternative energy substrate. The use of this diet is associated with a change in the proportion of fatty acids, mainly with an increase in the supply of saturated fatty acids, as well as contributes to water and electrolyte disturbances. In the literature on the subject, there are several described cases of ketoacidosis during the use of this diet. In addition, its long-term use increases protein catabolism, predisposes to the development of malnutrition. Moreover the high supply of fat in this diet increases oxidative stress and inflammation, which creates a carcinogenic and mutagenic environment. The vascular system, kidneys and nervous system are particularly susceptible to reactive oxygen species, hence it has been suggested that KD may contribute to the faster progress of aging processes and the development of age-related diseases.

Summary:
The inadequate supply of nutrients observed during following KD carries many risks. Due to the multitude of side effects and the lack of evidence confirming the safety of using a ketogenic diet, it should not be recommended to the elderly.