A ketogenic (called keto) diet is a very low carbohydrate, moderate protein and high fat diet. Those on a ketogenic diet reduce their total carbohydrate intake to only 5-10% of their total energy intake (which equates to approx 20-50g carbs per day), and by doing so, the body starts to break down fat and produce ketone bodies as its primary fuel. This process is known as ketosis.
The ketogenic diet originally gained interest as a medical dietary therapy for certain conditions including children with epilepsy, some cancers such as brain cancer and as a short-term treatment to reduce blood sugar levels in those with type 2 diabetes (under medical supervision). More recently, keto has also grown in popularity as a weight loss diet (in healthy people), and is associated with some benefits, including weight loss and improvements in blood glucose and blood pressure. It is important to note that studies conducted so far have been short-term, so we really don’t know the long-term benefits/effects of the keto diet.
The restrictive nature of this diet also means eating a well-balanced keto diet takes careful planning, and is difficult to maintain long term, which is a critical point. Similarly, the keto diet tends to lack diversity, especially of fruits and vegetables and is low in dietary fibre. We know diet variety and high fibre intake is associated with a plethora of health benefits. Finally, the keto diet is often high in saturated fats (e.g., cheese, cream, meat) with a high saturated fat content placing us at higher risk of several diseases. Therefore, if you are following a keto diet, it is important to choose healthy sources of fat, such as olive and macadamia oil, nuts, seeds, oily fish and avocado.
The ketogenic diet is also not suitable for some people, for example those that are pregnant, or breast feeding should not do keto. Additionally, many women find that the ketogenic diet affects their hormones. This can disrupt their menstrual cycle, including resulting in loss of periods (which may sound like a bonus, but is not good for your body!) and raise cortisol, your stress hormone, which in turn can encourage weight distribution around your waist. Not to mention the other host of unpleasant side effects the keto diet can cause such as ‘keto fog’, bad breath, irritability and fatigue.
Take home message? We are all individual and the keto diet may work for some, with some evidence for health benefits. However, we really don’t understand the long-term effects of this diet, and it may be difficult to meet all your nutrient needs due to a low intake of wholegrains, fruit and many vegetables. Scientific evidence consistently demonstrates that the success of a diet is not its macronutrient ratio, but the ability to adopt long term and sustainable changes.