If you’ve ever looked into changing your diet or eating habits, you would have no doubt come across the ketogenic diet. But what exactly is it, and is it really better than other diet options?

Although considered by many to be a recent “fad” diet, the ketogenic diet has a long, documented history of use as a therapeutic aid for a number of conditions. Since the 1920s, the ketogenic diet has been used in the treatment of epilepsy and was the standard treatment for both type 1 and 2 diabetes until relatively recently, too. So, what exactly is it? The ketogenic diet is uniquely different to other diet options because it is very high in fat and low in both protein and carbohydrates. Switching to fat as the primary fuel source for the body triggers a change in energy production in the body that is akin to how the body operates during starvation. The classic ketogenic diet (the one originally developed for managing epilepsy) also has restricted calories and fluid intake, in order to better mimic the effects of fasting on the body.

During fasting, the body switches from using primarily carbohydrates for fuel to instead utilising fat as a fuel source. The liver breaks down fatty acids released from the body’s fat stores and breaks these down into products called ketone bodies (or simply “ketones”), namely beta-hydroxybutyrate, acetoacetate and acetone (yep, acetone). This is a state known as ketosis. Ketones are considered a “super food” for the brain and can even be considered a “super fuel” for the body in general, because ketones produce more ATP energy in the body than glucose does. ATP energy is the main method of energy production throughout the body. Essentially, the body becomes more efficient at producing energy. The ketogenic diet forces the body into a state of ketosis by severely limiting the intake of carbohydrates, forcing the body to utilise alternate methods of energy production. Some detractors of this diet type argue that it goes against the body’s natural metabolic preferences to force it into ketosis, but there is evidence to suggest that the body can thrive in this state. Interestingly enough, human nutrition actually begins with ketones! Colostrum, the special breast milk produced in the first few days after birth, is ketogenic and provides all the nutrition newborns require in those first few days of life.

So, exactly how low do carbohydrates need to be in order to put the body into ketosis? To reach (and stay in) ketosis, carbohydrates need to make up less than 10% of total caloric intake. By contrast, the typical Western diet is made up of anywhere from 45-65% carbohydrates. The classic ketogenic diet requires around 90% of calories to come from fats, with the remaining 10% split between protein and carbohydrates (6% for protein and just 4% for carbohydrates). This strict restriction of carbohydrates and protein is difficult to adhere to and requires very careful planning and weighing of foods to meet requirements. The modern ketogenic diet more commonly followed in recent times is less strict than this, simply requiring the carbohydrates be 10% or less of daily calories and fat to make up 70% or more, without requiring weighing of food or restricting fluid intake. It’s important to note that even in ketogenic diets we still require some carbohydrates in our diet, as not all of our cells and organs can use ketone bodies for fuel. Red blood cells, for example, are only able to produce energy from carbohydrates and glucose. Similarly, the liver can’t use ketones, as it lacks an important enzyme needed for the ketone pathway.

Conditions that Can Benefit from the Ketogenic Diet


Epilepsy is one of the most well-documented conditions that benefits from the ketogenic diet. Even in Ancient Greece, the benefits of fasting for epilepsy were known, and the classic ketogenic diet was specifically designed to mimic fasting and assist in the treatment of epilepsy. Nowadays, the ketogenic diet is used primarily for those with refractory epilepsy – that is, epilepsy that does not respond to anti-seizure medications or surgery. There are several different ways by which the ketogenic diet helps in epilepsy management. Firstly, switching to ketones as an energy source for the brain increases the brain’s energy reserves, stabilising neurons and reducing the “excitability” of the synapses (the connections between brain cells), reducing the tendency for seizures. Interestingly, research suggests that some of the benefit of the diet may also come from its effect on the gut microbiota. With reduced intake of carbohydrates, there is less fuel available for bacteria to consume in the bowels, leading to changes in the types and amounts of bacteria in the gut. Bacteria in the gut are able to impact neurological functioning through the production of a number of different neuroactive molecules, including GABA and glutamate, which can affect brain functioning and shift the balance of neurons in the brain towards a lower likelihood of seizure. A recent study on mice found the ketogenic diet resulted in marked increases in specific bacteria including the Parabacteroides bacteria species and led to reduced seizure activity in epileptic mice.


Until the development of synthetic insulin in the 1920s, the ketogenic diet was routinely used for both type 1 and type 2 diabetes management. Numerous studies on the effects of ketogenic diets in diabetes management have found it to be an effective treatment strategy. In as little as 14 days on a ketogenic diet, patients experience improved insulin function, reduced blood glucose and cholesterol levels and even begin to lose excess weight. In longer term studies, these markers continue to improve with ongoing use of the ketogenic diet. Even with the use of insulin for diabetes management, ketogenic diets can improve the health outcomes and reduce medication requirements for those with diabetes.

Obesity and Weight Loss

The ketogenic diet is often touted as a weight loss aid, and certainly the evidence is there to back up these claims. High fat diets are typically more effective than other diets in the management of obesity in part because of their improved satiety – people on a ketogenic diet simply feel less hungry between meals, which helps with sticking to the diet. Consuming lower levels of carbohydrates reduces the output of the hormone ghrelin, which is the hormone responsible for making us feel hungry. There are also other ways the ketogenic diet can help with weight loss. A recent study found that the ketogenic diet, in combination with exercise, shifted skeletal muscles towards utilising more fat as fuel and resulted in improved insulin levels, even in already healthy, fit individuals. There is also a shift in the body towards increasing the breakdown of body fat for fuel, and reduced substrate available for the body to replace body fat stores, as this process requires glucose. Studies on obese patients have found that the ketogenic diet not only helps with reducing body weight but also cholesterol and even blood pressure.

There is, however, an important caveat to discuss when it comes to the supposed “miracle” weight loss people experience when they first begin this diet. Whilst the ketogenic diet is good for weight loss it is important to note that at least some of the very early weight loss experienced by people who start the ketogenic diet is actually loss of body water. A certain level of water is required for glycogen storage in muscles and other tissues. When we suddenly severely limit our carbohydrates intake, our body uses up/ empties our glycogen stores, which leads to a sudden reduction in water weight. This process is also why people experience a rapid increase in weight when initially moving away from a ketogenic diet. The sudden increase in body water when moving out of ketosis is often falsely believed to be a sudden regaining of lost body fat, and unfortunately can unnecessarily deter people from stepping away from the ketogenic diet when it is no longer serving them.


PCOS (polycystic ovarian syndrome) is a common hormonal condition, affecting up to 20% of women of reproductive age. It’s a complex condition but involves the overproduction of androgens (“male” type hormones), increased body fat and insulin resistance, and can even lead to obesity and type 2 diabetes. Women with PCOS typically experience menstrual and fertility issues, and it can lead to depression and significantly affect quality of life. Studies examining the effects of diet on PCOS have found the ketogenic diet reduces the overproduction of androgens, leading to normalised hormonal function, improved insulin function and even lowering of depressive symptoms.

Mental Health

The ketogenic diet also generates interest with regards to the treatment of a range of mental health conditions, because of the effect of ketones on the brain. Research suggests ketogenic diets are neuroprotective, because of the way they change energy utilisation in the brain, which leads to improved cognitive performance and cerebral function. The positive mental health effects may also be due to the effect of ketosis on neurotransmitters. The ketogenic diet has been shown to increase levels of GABA (also known as gamma-aminobutyric acid), which is known for producing feelings of calmness.

Alzheimer’s Disease

It’s not surprising that the ketogenic diet has been used in the management of Alzheimer’s disease, which is sometimes referred to as “the diabetes of the brain”. Alzheimer’s is a complex and poorly understood condition, however one of the major pathophysiological processes that lead to symptom development is poor glucose metabolism in the brain, which leads to the development of plaques in brain tissue. The ketogenic diet may help to relieve this by providing an alternative fuel source to the brain in the form of ketones. Studies have found the ketogenic diet, in addition to being neuroprotective, also reduces the build up of amyloid on the brain.


Interestingly, the ketogenic diet may also be beneficial in managing IBS symptoms. Part of this is due to the reduction in carbohydrate intake and the effect this has on the microbiome. In IBS, there is often an imbalance of gut bacteria (known as dysbiosis) and/or an overgrowth, which can lead to excessive fermentation in the gut in response to eating carbohydrates. The reduction in carbohydrates reduces the food source available for bacteria to ferment, in turn reducing the number of bacteria present in the gut (and reducing their effect on our health, too).


A growing body of evidence suggests that the ketogenic diet might even be a useful tool in the battle against cancer. One of the primary ways it has been proposed to be of benefit is through the phenomenon known as the Warburg effect. Cancer cells prefer to use glucose for energy and are less able to use ketones as a fuel source when glucose becomes unavailable. By reducing the availability of glucose for energy consumption, the ketogenic diet can “starve” the cancer cells, limiting the ability of tumours to proliferate and grow. So far researchers have demonstrated this effect of the diet on brain, breast, colon, endometrial and prostate cancers. However, it’s important to note that the ketogenic diet in itself is of course not going to be a cure for cancer, although with more research it may form one tool for the cancer treatment toolkit.

Cons and Contraindications

The ketogenic diet is not without its side effects, some of which can be significant. Common mild side effects include headache, diarrhoea, constipation, and insomnia. Long term, the ketogenic diet can lead to deficiencies in minerals such as zinc, calcium and selenium, as well as low vitamin D, so it is important to have appropriate supplementation whilst on this diet.

Another significant con of the ketogenic diet is its hormonal effect, particularly in women. The low levels of fibre in the diet impact not only our gut microbiota but also our hormone levels. Fibre is crucial for the excretion of excess hormones such as oestrogen. Without sufficient dietary fibre, oestrogen and other hormones that would normally have been excreted are reabsorbed in the gut and re-enter circulation in a process known as “enterohepatic recycling”. This leads to an increase in circulating oestrogen levels, which can wreak havoc on women with conditions exacerbated by hormonal changes, such as endometriosis, PMS, and even menopause. The low levels of complex carbohydrates can also trigger an increase in cortisol production, which can further exacerbate menopausal symptoms. In women, elevated oestrogen levels can also suppress thyroid hormone production. Our thyroid hormones are responsible for metabolism – suppressing them can lead to weight gain, decreased energy levels and low libido. So, although women may lose weight initially, the effects of ketosis on thyroid hormones and metabolism may end up leading to weight gain in the long term. In fact, the suppressing effects of the ketogenic diet on thyroid hormones are so marked that in some patients on the ketogenic diet for epilepsy, synthetic thyroid hormone replacement is required. These effects on thyroid hormones also mean that the ketogenic diet may not be recommended for those who already experience thyroid hormone issues.

The overall health of gut microbiome which is the ecosystem of bacteria and other species is a major consideration whenever a keto diet is implemented long term.  With a range of carbohydrates representing the main food source for healthy species, reducing nutrient rich carbohydrate foods can have significant implications on mental health, immune system and much more.

Whilst the ketogenic diet can have fantastic results in helping to manage certain conditions and can be used for short-medium term health strategies, it’s not without its limitations and risks. Because of this, it’s vital to speak with a professional before embarking on a ketogenic diet, to make sure you are set up for success with your health.  Naturopathic expertise can point you in the right direction and give you the tools required to support optimum short, medium and long-term health.  This way you know whether this kind of diet is appropriate and for how long it should be used in your unique situation.


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