Ketogenic diets are becoming increasingly popular. As a weight loss tool, as a performance enhancer and for other health benefits. No matter the reason behind your consideration of the ketogenic diet, it is important to understand the relevant evidence.
What is the Ketogenic Diet?
The ketogenic diet is traditionally high fat low carbohydrate. However, there is some debate over the exact definition of ‘low’ and ‘high’. A popular figure is 80% of calories coming from fat. In reality, this is extremely hard to achieve. In order to consume 80% of calories coming from fat, your diet must consist of mainly egg yolks, nuts, dairy, meat and oil. You can throw in a select few vegetables if you feel like shaking things up!
Another common definition of the ketogenic diet is having less than 20g of carbohydrate per day. This is a little over one serve. This means you could have just over 1 piece of bread, one tub of yoghurt, 1 medium apple, 1/3 cup of cooked rice or 1 cup of milk. And that’s all you get. For the whole day.
No matter which way you look at it, the ketogenic diet is tough. Say goodbye to pleasures such as potato, fruit, peas, legumes and corn. Not to mention the good stuff like alcohol, sweets, pie, pasta and chips! This begs the question, why on earth are people doing it?
For Weight Loss
Given the current obesity crisis, and our ever-increasing waistlines, the public is becoming increasingly desperate for a magic diet that fixes it all. Some people think the ketogenic diet is just that. While there is evidence to suggest the ketogenic diet is an effective tool in weight loss, the research is in its early days and somewhat flawed.
First off, we don’t just want to lose weight for a mere couple of months. We want weight loss to be maintained for the remainder of our lives. The whole point of a weight loss diet is to be sustainable. The last thing we need is another yo-yo diet to add to the ever-lengthening list. While it is great that research has found that the ketogenic diet is ‘undoubtedly effective in short to medium term weight loss’, what about the long term? No one wants to lose weight just to gain it all back again. Currently, the longest study in ketogenic diets is a measly 24 weeks in duration. My prediction (disclaimer: this is only a prediction), is that in studies exceeding the 12month mark, the weight loss results will weaken. The ketogenic is unsustainable for the vast majority, of whom, will inevitably fall off the band wagon and regain the weight. While this is a grim outlook, and believe me, I wish it weren’t true, fad diets tend to follow a similar trajectory.
Firstly, let me make a distinction between weight loss and health. While it is healthy to lose weight (if you are over-weight), and a lot of people losing weight are doing so for health reasons, there is a difference between the use of ketogenic diets for weight loss and for health. When I refer to dieting for health, I am referring to a desire to improve cardio metabolic markers and blood profiles, for the purposes of chronic disease prevention. Weight loss may incidentally accompany this, but they are not one in the same. Evidence suggests that a ketogenic diet can improve the blood lipid profile in 24 weeks, contributing to a lowered risk of cardiovascular disease. However, in this study, the ketogenic diet specifies 80% of calories must come from poly and monounsaturated fats. In practice, most people following a ketogenic diet would not be reaching this target and are likely to have a greater reliance on unhealthier fat sources such as saturated animal fats. Furthermore, the study did not compare the participants blood lipid profiles to a control. Hence, these sorts of blood lipid improvements might be seen on any weight loss diet and may not be special to ketogenic diets.
Furthermore, a very low carbohydrate means very low intake of carbohydrate nutrients. For example, thiamine, folate, potassium, calcium, magnesium, vitamin A, E and B6 are all at risk of deficiency if the ketogenic diet is not well balanced. A ketogenic diet is also generally lacking in fibre, which is counterproductive to health.
For Athletic Performance
High end athletes have been trialling the ketogenic diet in the pursuit for optimised performance. Sadly, not everyone has seen success. Ketogenic diets may be ergogenic in the context of ultra-endurance athletes. Ultra-endurance refers to gruelling events that last longer than 4-5 hours. For example, marathons upwards of 80km. Yes, such intensive sports exist and yes, some crazy dedicated individuals do compete. While I may not understand the someone’s motivations to run for hours on end, I can understand wanting to do it easier and faster. After hours of exercise, the body’s glucose (carbohydrate) stores become depleted. At this point, known as ‘hitting the wall’, the body shift from using glucose as a primary fuel, to using ketones bodies and fat. Since this is type of glucose starvation is unusual for our bodies to experience, they are not particularly proficient at using fat as a fuel. Hence, athletic performance takes a serious hit and most people can perform at a maximum of 50% intensity. Unless of course, your body is accustomed to a carbohydrate deficiency and using fat as a primary fuel. Cue ketogenic diet. If the body is constantly exposed to high fat, low carbohydrate, it has the capacity to adapt and more efficiently use fat. However, everyone’s extent of adaptability is different. Where some people might see large success in fat-adaption, some may not. Hence, the diet is not suitable to every athlete. Furthermore, no matter how well you have fat-adapted, you will never be able to perform at the same intensity as you might on carbohydrate fuelling. This means that for those on ketogenic diet, high intensity sprints are near impossible, which may be inhibitory to performance. Imagine you are at the end of a race and the difference between second and first is a final sprint to finish. Could ketogenic supplements be the solution to this problem?
Evidence is emerging to suggest the use of a ketogenic diet in the management of epilepsy, in the paediatric population. While there is still a lot we don’t know about this novel treatment, the ketogenic diet has been found useful in the management of epilepsy symptoms.
The Low Down
Ketogenic diets are used for a variety of purposes, and the evidence surrounding ketogenic diets is still emerging. If you are considering following a ketogenic diet, please consult with a dietitian in order to prevent yourself harm and to help you achieve your goals, whatever they may be.
Renae Earle is a Masters of Dietetics student at the University of Queensland. Having achieved her Bachelor of Exercise and Nutrition Science with distinction, she is motivated to complete her studies and become an accredited practicing dietitian.
Renae is passionate about evidence-based practice and debunking nutrition myths. She believes that in today’s fad celebrity diet culture, it is increasingly important to deliver the facts. She aims to help people achieve a sustainable and healthful lifestyle by combating the flurry of misinformation offered by tabloids and social media.
In order to achieve this goal, Renae has dedicated herself to the field of nutrition. She is well educated on a wide range of nutrition topics such as supplementation, chronic disease, restrictive diets and metabolism.
Renae has a keen interest in offering personalised nutrition plans that suit the specific needs of her future clients.