The Ketogenic Diet

The ketogenic diet (KD) is a very restrictive, high fat, low carbohydrate diet that started out as a treatment for uncontrollable epilepsy. Research has shown that it can be effective at reducing seizures in people for whom the typical medications and other seizure treatments are not fully effective. In recent years, however, the ketogenic diet has become popular for everything from weight loss and autoimmune disorders to cancer treatment.

The general idea behind the KD is that by eating a very high ratio of fats to carbs and proteins the body will enter the metabolic state of ketosis. This means the body burns through fat stores and uses ketones for energy instead of digesting carbohydrates and using glucose for energy. The most common ketogenic ratios are 4:1 and 3:1. A 4:1 ratio means that a person would consume 4 grams of fat for every one gram of protein plus carbohydrate, so for every 5 grams of food consumed, 4 of them are fats and the last 1 is protein and/or carbohydrates. The recommended foods to eat on the KD include seafood, low carb vegetables, cheese, avocado, meat and poultry, eggs, coconut oil, and plain Greek yogurt. It is important to not eat foods that are high in sugar, and also to make sure that the chosen fat sources are generally healthy fats, not processed.

How does the ketogenic diet effect the gut microbiome?

All the foods we eat impact our gut microbiome in positive or negative ways. As many more people are adopting a ketogenic-style diet, it is important to look at whether this is helpful or harmful to the microbiome. The link between the KD and the gut microbiome is only just beginning to be researched. More studies need to be done on how the KD affects the microbiome, and also on what consequences those changes may have for a person’s overall physiological health. However, some general conclusions can be drawn based on what research is currently available.

One recent study looked at the relationship between epilepsy and the gut microbiome using mice to study the effects of the KD on the microbiome. First, they found that within four days of being on the diet the gut bacteria were changed drastically. Two species of bacteria in particular, Akkermansia and Parabacteroides, were found in high amounts in the gut microbiomes of the mice that were fed ketogenic diets. These bacteria work together to provide seizure protection by reducing production of a certain glutamyl enzyme in the gut, which leads to less production of glutamate (a neurotransmitter that activates neurons). With less glutamate being made there is more GABA to quiet the neurons, which leads to fewer seizures. The result is that mice fed the KD had higher amounts of Akkermansia and Parabacteroides in the gut which led to increased seizure protection for those mice.

In another recent study, 217 healthy adults were given one of three diets with different percentages of calories from fat. They found that over a six-month time period, the gut microbiome of the people on a high fat diet had changed in ways that could negatively impact overall health. One group of bacteria in particular decreased in those eating a high fat diet, and increased in those on a low-fat diet. Some of this bacteria group is responsible for producing short-chain fatty acids that help regulate inflammation in the body as well as protect the cells lining the intestines. This means that the ketogenic diet may lead to bacterial changes that could have a negative impact on people’s health in the long term.

Higher diversity in the gut microbiome has been shown to have positive effects on overall health. Current research on the KD in healthy individuals has found that the diet actually reduces gut microbiome diversity. This is thought to be the case because many groups of bacteria rely on carbohydrates for energy and cannot adapt to the low carb, high fat nature of the diet. These bacteria will then suffer, and the bacteria that are better suited to using fats for energy will increase in number. While certain bacteria that are more prosperous under ketogenic conditions have beneficial effects for health, as is the case with those that increase seizure protection, the current thought in the field is that the overall lower microbiome diversity may lead to more health problems later.

The ketogenic diet was designed for specific clinical applications, such as controlling seizures in people who don’t respond to other treatments. It was not designed as a diet to support general health or weight loss. While it may be helpful for other conditions or issues, it is wise to consider the potential risks along with the benefits when adopting a diet this restrictive. From the standpoint of the gut microbiome, current research indicates that despite some short-term benefits, following the diet without a specific need may not be in the best interests of one’s gut or overall health.



Dr. Nicole Beurkens, PhD, CNS

Licensed Psychologist and Board Certified Nutrition Specialist

The world’s leading Holistic Child Psychologist, Dr. Beurkens heads a multidisciplinary evaluation and treatment clinic, is a bestselling author, published researcher, award-winning therapist, and devoted mother of four. In her more than 22-year career, she has supported parents with evidence-based strategies that target the root cause of children’s attention, anxiety, mood, and behavior challenges, empowering them to achieve their highest potential. Dr. Beurkens is a licensed clinical psychologist who holds advanced degrees in psychology, education, and nutrition.

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