First up, what is the ketogenic diet?
A ketogenic diet relies on fat as the key source of energy, while severely limiting carbohydrates, and allowing moderate amounts of protein. As the main source of energy, the body breaks down fat for energy, which leads to a build up of acids called ‘ketones’ in the body. This process is known as ‘ketosis’. The body enters ketosis when carbohydrate intake is reduced to around 50g per day, or less – the equivalent of around two slices of bread, and a banana.
Where did it come from? It seems to be having a bit of a resurgence, has it always been popular?
There has been a renewed interest in low carbohydrate, high fat (LCHF) diets in recent years, after their first wave of popularity in the 1970s. Amongst the many variations of these is the ketogenic diet – an eating pattern very low in carbohydrate foods, so energy mainly comes from fat.
How does a ketogenic diet differ from other low carbohydrate, high fat diets?
Many popular diets encourage short stints of a very low carbohydrate intake to bring on ketosis to ‘kick-start’ weight loss. This may begin with periods of eating as little as 20g of carbohydrates per day, and slowly increasing to more than 50g per day.
But the difference between a low carbohydrate, high fat diet and a true ketogenic diet is that the latter remains proportionately lower in carbohydrates – 20-50g per day, and less than 10 per cent of total energy, keeping the body in a state of ketosis. This differs significantly from the recommendations set out by the Australian Dietary Guidelines, which are intended for healthy populations, that suggest between 45-65 per cent of energy come from carbohydrate foods.
The most recent Australian Health Survey in 2011/2 determined that the average Australian only consumed 43.5 per cent of energy from carbohydrates – less than the minimum recommended amount.
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Does evidence support the ketogenic diet?
Although many books and websites tout a ketogenic diet for a wide range of health benefits, in reality the diet is backed by very limited evidence in healthy individuals.
However, there is established research supporting its success as a medical intervention for epilepsy, particularly in paediatric and childhood cases. Epilepsy is a common, chronic neurological disorder characterised by recurring seizures, and though the exact mechanisms are unknown, a ketogenic diet has been found to reduce frequency and severity of seizures. ketogenic diets have been used to treat epilepsy in children since the 1920s, and are only recommended to be trialled with full support of a multidisciplinary medical team, including dietitians, neurologists, nurses, pharmacists, and social workers. A dietitian’s support is vital, as a ketogenic diet is very restrictive, so nutrient needs must to be constantly monitored, and support offered to the child and caregiver.
There is growing interest in the effect of a ketogenic diet in patients with cancer, particularly brain tumours. While the current research and preliminary results from clinical trials suggest a ketogenic diet is safe, and may show anti-cancer and neuroprotective effects, there are various limitations to consider. Much of the current evidence is observational, undertaken in small populations, and in animals, so further research is needed before strong conclusions can be drawn.
What are your thoughts on it from a dietitian's standpoint, is it healthy and beneficial to weight loss?
Following a ketogenic diet will undoubtedly result in short-term weight loss, which probably comes down to a reduction in kilojoule intake, the depletion of liver and muscle glycogen stores and associated water, and a reduced appetite caused by eating more satiating fat and protein-rich foods.
A strict ketogenic diet is undoubtedly difficult to stick to without drastically reducing whole food groups.
You’re also missing out on nutritious foods and the nutrients they provide.
Carbohydrate-containing foods, such as breads, cereals, rice, pasta, legumes, fruit, and starchy vegetables (like pumpkin, peas, and potato) must all be limited. This is a challenge, not only for maintaining optimal health, but also for food enjoyment – including in family and social situations.
A note on wholegrains:
Eating wholegrains is linked with a reduced risk of health conditions like type 2 diabetes, cardiovascular disease, largely due to their fibre content and other protective components called phytonutrients. A major review of 304 meta-analyses and systematic reviews even found grain foods are more protective than fruit and vegetables against diet-related chronic diseases.
And fruit and vegetables:
Fruit and vegetables are, however, an excellent source of many vitamins, minerals, dietary fibre and other phytochemicals that keep each of our cells healthy. With only one in two Australians currently meeting the recommended two-a-day serves of fruit, it’s clear that following a ketogenic diet would make the target near impossible.
The take home message:
Though it may offer some metabolic benefits when followed in the short-term (a few months), and pose as a novel treatment for certain medical conditions, a ketogenic diet isn’t recommended for the general population, as the long-term efficacy and safety of the diet are unknown.
For this reason, if you choose to undertake a ketogenic diet, this should be done under clinical supervision – with the guidance of a health professional, such as an Accredited Practising Dietitian. And as always, when it comes to nutrition, it’s important to remember that there is no one-size-fits-all approach.
Nicole Dynan is an Accredited Practising Dietitian, Accredited Sports Dietitian, Accredited Wellness Coach and Owner of The Good Nutrition Co