Ketogenic diets (very low carbohydrate diets), have been around since the 1920s when they started being used as a treatment for epilepsy.
These diets became famous around forty years ago in the form of the Atkins diet – and have since been reinvented under various different names.
Have you ever considered going on a ketogenic diet? But before you head out to buy your ketone testing sticks (urine), you need to know more about what ketosis really is, and if your health will benefit by going on a ketogenic diet.
What is ketosis?
Glucose metabolised from carbohydrates is the body’s preferred energy source. Ketosis is the process whereby your body (specifically your central nervous system) is forced to utilise an alternative source of energy, when your diet has been depleted of glucose. A state of ketosis is achieved when a diet containing less than 50 g of carbohydrate per day is followed for around 3–4 days.
When your carbohydrate stores have been completely depleted, the body is forced to use another form of fuel. The central nervous system is unable to use fat as fuel, but it can use ketones (metabolites of fat).
When an individual is in a state of ketosis, ketones will be present in their blood and urine. They will be able to confirm their state of ketosis with the use of a ketone-sensitive urine stick. People in ketosis often have a “sweet, fruity” odour on their breath, due to the elimination of excess acetone.
What makes the ketone diet special?
- The role that ketosis plays in weight loss, and its protective role in diseases
There is some evidence which supports that a ketogenic diet can facilitate weight loss. It is suggested that this diet may contribute to weight loss via the following mechanisms: the satiety effect of ketone bodies; the reduction in lipogenesis (fat building) and increase in lipolysis (fat breakdown); and the increased metabolic efficiency when consuming fats and protein as opposed to carbohydrates.
There is however controversy regarding whether these are truly the cause of weight-loss or whether it is simply due to the caloric deficit that is achieved when carbohydrate intake is limited, together with the satiety effect of protein. Research indicates that regardless of the type of diet you choose to follow, when a kilojoule deficit is created, weight-loss will occur.
Read: Carbo-loading considered
A review of the therapeutic effects indicates that this diet may have a protective effect in the case of cardiovascular disease by improving cholesterol profiles (specifically triglycerides). It may also have a positive effect on diabetes and insulin resistance; acne; cancers; and polycystic ovary syndrome. However, the benefit may be due to the weight loss rather than the characteristics of the diet.
A ketogenic diet has been used since the 1920s to treat seizures, and has shown to be effective in people with genetic disorders that result in a condition whereby the brain is unable to derive adequate fuel from glucose. These people benefit by using ketones as an energy source.
A recent review of evidence showed a reduction of 30–40% of seizures compared to the controls, although the dropout rates were high due to the difficulty in sustaining a ketogenic diet. More recent research has shown following a ketogenic diet to be beneficial as part of the treatment of Alzheimer's disease
Concerns of health professionals: sustainability and safety
Sustainability is a key concern for health professionals as this is the aspect that most people will find the most challenging. A very low carbohydrate ketogenic diet is not easy to sustain indefinitely. As mentioned earlier, to achieve a state of ketosis, carbohydrate intake needs to be limited to a consistent 50 g per day.
Read: Watch those carbs!
This equates to a carbohydrate intake of 1 cup of wholegrain carbohydrates (such as corn, bulgur wheat, or quinoa) and 1 portion of fresh fruit per day. All other foods such as milk and milk products, whole grain carbohydrates, fruits and vegetables need to be excluded as they will all increase the carbohydrate intake and prevent ketosis from occurring. Although this may be achievable for a short period, long term sustainability of this diet is questionable.
Restricting carbohydrate intake so severely results in the individual having to eliminate or restrict major food groups in the diet. Of particular concern is the elimination or restriction of fruits and vegetables, low fat dairy as well as high fibre, whole grain carbohydrates. These food groups provide a variety of vitamins, minerals, antioxidants and fibre which are important for maintaining gut health, immunity and health in general.
Of further concern is the potential damage that may be done to the kidneys due to high levels of nitrogen excretion that occurs during protein metabolism when this high protein diet is consumed indefinitely.
A ketogenic diet may be beneficial for the treatment of a few mental conditions. With regard to weight loss, sustainability of the ketogenic diet was a key issue in those partaking in the studies and therefore this, together with safety of the diet need to be considered before opting to follow this style of eating.
1. Gibson A, Seimon R, Lee C, Ayre J, Franklin J, Markovic T, Caterson I, Sainsbury A. Do Ketogenic diets really suppress appetite? A systemic review and meta-analysis. Obesity Reviews 2014: 1 – 13.
2. Mahan LK, Escott -Stump S, Krause’s Food Nutrition and Diet Therapy 14th edition Philadelphia, Saunders 2016.
3. Paoli A, Rubini A, Volek J, Grimaldi K. Beyond weight loss: a review of the therapeutic uses
of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition 2013; 67:789-796