What the health: Ketogenic diet - fix or fad?

27 Feb 2019

Ketogenic diet - fix or fad?Is this diet a fad? No, the ketogenic diet in itself is not a fad, but the reason why it is practiced, and how it is practiced may be!

Foods contain macronutrients (protein, carbohydrate and fat), micronutrients (vitamins and minerals), and a variety of other health promoting constituents (fibre, phytonutrients). Macronutrients are building blocks for the body, and yield energy that the body uses to produce its fuel.

The National healthy eating recommendations for the proportion of carbohydrate, protein and fat in the diet are 45 to 65 per cent, 15 to 25 per cent, and 20 to 35 per cent of total daily energy intake respectively. These recommendations are addressed to the healthy general population. They aim to ensure the provision of essential micronutrients and other constituents as well as energy through foods alone (as opposed to supplementation) for optimal health sustenance. But is this proportion of macronutrients the only way to eat healthily? Not necessarily.

Macronutrient “manipulation”, or changing the proportion of each macronutrient in the diet, can be individualised for optimising dietary needs and health goals. New understandings of genetic individuality in terms of metabolism, and current health status, suggest that dietary plans with varying ratio of macronutrients may be indicated to achieve individual optimal health outcomes.

The ketogenic diet is by definition a diet that promotes the production of ketone bodies (KB). KB are molecules produced in the liver as a result of using fat (dietary or from body stores) as primary source of energy. KB are released into the circulation, and delivered to muscles, the heart and the brain where they are converted to fuel. In the last few years, research in the field of metabolism and healthy ageing has revealed the health benefits of KB beyond providing energy.  KB are shown to promote anti-inflammatory, anti-antioxidant, and autophagy (cell “spring cleaning”) pathways, and mitochondrial genesis, ultimately resulting in healthier metabolism, better immunity and organ function.

Ketogenesis occurs when one is fasting, or restricting energy intake long term (body fat stores are being used as energy source), or when modifying the proportion of macronutrients in the diet to favour a high fat intake whilst reducing carbohydrate intake. Gut hormones secretions appear modified to help with appetite control; and more enzymes required in fat utilisation are produced, potentially resulting in more efficient fat oxidation and thus benefits for weight control.

In a typical ketogenic diet, carbohydrate provides only up to 10 per cent, protein between 15-25 per cent and fat up to 80 per cent of total daily energy intake. For a 8000 kilojoules daily energy intake, this means approximately 47 g of carbohydrate, 178 g of fat and 71-118 g protein. Ketogenesis can be monitored by finger prick blood test, with concentration of KB varying between 1- 5 mmol/L. Nutritional ketosis (rise in KB concentration) is different than diabetic ketoacidosis, where the concentration of KB reach levels 25 mmol/L, which impacts dangerously on blood acidity (pH).

The ketogenic diet has been used to manage refractory (treatment-resistant) epilepsy in patients since the early 1920’s, including in children, with over 750 peer reviewed articles on the topic. This is because KB act as a steady supply of energy for the brain and have an anticonvulsant and antiepileptic effect. The protocols strictly limit carbohydrate intake, which restrict food options and requires careful meal planning, with fibre and micronutrient supplementation. In children with epilepsy following the diet, long term follow-up has shown incidence of stunting, kidney stones and bone demineralisation in 13-20 per cent of patients, highlighting the importance of professional support. To date,  there are no long term follow up adult studies looking at the impact of the ketogenic dietary pattern on general health.

A ketogenic diet is therefore a low carbohydrate-high fat (not high protein) diet. When excluding foods in the diet, it is important to consider what nutrients are being jeopardised in the process. The type of fat consumed is paramount, and so is the composition of the small intake of carbohydrate. Indeed, well selected sources of carbohydrate (leafy and colourful vegetables) will also provide fibre, vitamins and minerals, which would otherwise be limited in this dietary pattern.  Savvy meal planning or supplementation is required. Furthermore, excluding foods may lead to cravings, or may be difficult to adhere to in social situations. For all these reasons, it is advised to seek guidance from dietitians to receive the support and right assessment on whether such dietary plan is suitable, as well as which protocol.

Different protocols of the diet are currently being investigated for the management of neurological conditions, the control of blood sugar levels in type 2 diabetes, increasing athletic endurance, or to assess its efficacy in the control of glycolytic tumour growth, concurrently with treatment.

Therefore, rather than a fad, the ketogenic diet is a therapeutic nutritional approach. Biochemical mechanisms must be well understood, and individualisation for the targeted goals and adherence must be applied.  

Dr Veronique ChachayAuthor: Dr Veronique Chachay is from UQ's School of Human Movement and Nutrition Sciences. Dr Chachay's research interests include the nutrient-gene relationship in the context of health and ageing disease, brown adipose tissue recruitment and activation, diet-induced thermogenesis in the management of obesity, the genetic characterisation of individuals following exclusive dietary patterns, as well as the effect of exclusive dietary patterns over time in the context of ageing and longevity.