The ketogenic diet or ‘keto’ was first devised in the 1920s, but not with weight loss in mind. It was initially designed for the treatment of childhood epilepsy. Indeed, the keto diet is, in fact, an effective method of controlling epileptic seizures which are still used to this day, although its therapeutic mechanism has yet to be determined. The widespread appeal of the ketogenic diet can be attributed to its emphasis on hyper-palatable foods such as bacon, steak and butter, all while promising impressive weight loss results, not to mention claims of miraculous health benefits such as curing cancer and dramatically improving athletic performance. It has become particularly popular in Silicon Valley and is endorsed by celebrities such as Kim Kardashian and Halle Berry.
But is the ketogenic diet just another addition to the long list of diet trends, or is it legitimate? The demonization of carbohydrates has long been engrained into diet and weight loss culture. Low-carbohydrates diet became and stayed popular with the advent of the Atkin’s diet in the 1970s, devised by the cardiologist Robert Atkins. The diet reached the pinnacle of its success in the early 2000s, with as many as one in eleven North Americans claiming to be following the diet. Despite much evidence that the diet achieves pretty moderate weight loss results in comparison with basic energy restriction (and may increase the risk of heart disease) the low-carbohydrate diet, or some variation of it, has stuck around.
However, unlike other low-carb diets which typically emphasise protein as the main macronutrient, the keto diet focuses on fat. A ketogenic diet forces the body into a state of ketosis, typically after five days of following the diet. Ketosis is a physiological process by which the body breaks down stored fat into molecules called ketone bodies. Cells will then begin to use these ketone bodies to generate energy that would normally be supplied by the glucose that comes from carbohydrates. Essentially, the body begins to burn fat instead of carbs for energy. The standard ketogenic diet consists of a split of 80% fats, 16% protein, and 4% carbs. To stay in the so-called ‘ketogenic state’, an individual should consume no more than 20-50g net carbs a day. One medium-sized banana is approximately 27 grams of carbs, so it doesn’t leave much leeway. The majority of the diet is made up of fat-rich foods, such as meat, eggs, cheese, fish, nuts, butter, oils and seeds. Only small portions of certain low-fructose fruits (usually berries) are allowed, as well as non-starchy vegetables. Foods that are not ‘keto-friendly’ include most grains, starchy vegetables, as well as legumes and large quantities of fruit.
The ketogenic diet has not been found to be significantly more effective at promoting weight loss than simple calorie restriction. Weight loss achieved on the keto diet may solely be attributed to ultimately less overall calories consumed overall, achieved by eliminating basically an entire food group, although high fat consumption has been shown to be associated with increased levels of satiety, which may aid weight loss. The initial dramatic weight loss that many report when transitioning to becoming ‘fat-adapted’ can be attributed to loss of water weight that is caused by carbohydrates stores in the body carrying water molecules with them. The main problem with recommending the ketogenic diet for weight loss is adherence difficulties; the diet is simply tough to stick to over long periods of time. There are many reasons for this, including impact on social life as well as the expense of animal products. The diet requires a great amount of discipline and vigilance, and any kind of dietary slip up could ‘push one out of ketosis’. Any weight loss strategy is made redundant if it is unfeasible to maintain in the long-term.
One of the many purported claims of the keto diet is its potential therapeutic utilisation in the treatment of neurological disorders apart from epilepsy, including migraines and multiple sclerosis. This claim is based on the alleged neuroprotective effect the diet induces. Although some trials are in progress, there is little clinical proof at present supporting these statements. The diet has also been promoted as being effective in the management of type 2 diabetes. It is thought to achieve this by improving control of blood glucose levels, and decreasing the need for diabetes medications. The ketogenic diet has been suggested to have applications in the treatment of some types of cancer. This is based on the concept that some cancer cells are inefficient at processing ketone bodies for energy. This claim has yet to have any seriously robust scientific evidence to support it at present, with any clinical studies testing it producing mixed results and achieving very low levels of success. In addition, the over-consumption of saturated fat-rich foods such as butter and bacon is linked to increased risk of colorectal cancer, thus achieving the direct opposite intended effect.
There’s a lot we still don’t know about the ketogenic diet. To date, the majority of studies have been done in mice, with little translation into human studies. For this reason, its many claims are supported only by anecdotal evidence, and while there is an overwhelming amount it does not amount to scientific evidence. Additionally, the diet’s restrictive criteria may leave followers of the diet at risk for nutrient deficiencies, as, if uncareful, their diet may lack the essential vitamins and minerals that fruit, vegetables, legumes and grains would supply. A 2019 study found that a high-fat diet followed for a six-month period led to ‘unfavourable changes’ in the gut microbiome of the subjects, which may lead to larger and more dangerous health implication in the future. In addition, the build-up of ketones in the body has a number of undesirable side effects. These include nausea, headaches, mental fatigue and bad breath caused by the acetone-smell of excess ketones. These symptoms collectively are often referred to as the ‘keto flu’.
Its rigidity and high cost mean it is not feasible for everyone, and there is a paucity of evidence to support it being more effective than any other diet for weight loss.
As for the ketogenic diet’s other supposed applications, bar epilepsy, the proof is weak and unconvincing.


By Grace Browne – Science Writer