The runner’s guide to the… ketogenic diet

ketogenic diet

There’s nothing more that runners like to talk about (other than running) than our nutrition and what we eat. Let’s face it, food is a pretty important part of our running and it can make all the difference in terms of performance too. But, different foods work for different people and there’s no hard and fast rules in the world of eating, other than to say do what’s best for you and seek out balance in your diet. To help you along the way, we’re presenting a series of articles that look at the different types of diet on offer to help you make your own informed decisions. There’s no preaching from the thrones here, just some basic information for you to consider. First up is the ketogenic diet…

For those on the ketogenic diet… carbs are out, fat is in… switching starchy goodness for full-fat delights. But where can you get some? Ketones aren’t something you buy; they’re inside your body. To be more specific, ketones are a type of organic substance produced naturally by the liver when it breaks down fat for energy.

Confused? Okay, let’s say you’re eating a standard, balanced diet. Your body gets most of its energy by turning carbs into glucose, which your cells then convert to energy. Glucose is the easiest molecule for the body to convert to energy, so it will always be chosen over any other energy source. However, on the ketogenic diet, you reduce carb intake typically to less than 50 grams a day. So rather than relying on carbs as its primary energy source, your body uses ketone bodies, which are derived from fat. This metabolic state is called ketosis.

During ketosis, the liver produces ketone bodies, which are then converted into substances that feed your cell’s energy production. So, if you’re an ultra runner in the state of ketosis, the theory goes that you can unlock extra fuel when they need it – in the late stages of a miler, for example. Ketosis is a natural metabolic process that our body jumpstarts to help us survive when we’re not eating much.

So if you cut down on the carbs, what can you eat?

The rules of the diet are pretty simple: limit your daily carb intake to 50 grams or less. Your recommended daily intake on a ketogenic diet is about 75% calories from fat, 20% from protein, and a mere 5% from carbs. So, you tuck into lots of those foods that are naturally high in fat, like cream, butter, certain nuts, meat, fish, green leafy veggies, healthy fats and oils. But it’s goodbye to bread, pasta and grains.

Sound pretty strict…? It is. There are also a few risks. For example, if you don’t take in enough salt, you might suffer from tremors and a rapid heartbeat, as an ABC reporter found out when she took on the ketogenic diet for six weeks.

But what about the famous runner carb-loading? Good question. Carb-loading programs are the antithesis of the keto diet, as they recommend eating around 500-700g of carbs a day. The Australian Institute of Sport (AIS) recommends that carbohydrates are a key fuel source for exercise, especially during prolonged continuous or high-intensity exercise. They say that eating carbs before exercise should assist in topping up blood glucose levels, as well as glycogen stores in the muscle and liver – which is especially important if the activity is high intensity or will continue beyond 90 minutes. They also say that replacing carbs during prolonged exercise can benefit performance.

So, is the keto diet just another one of those Atkins fads? It’s actually been around since the 1920s, when endocrinologist Dr Henry Rawle Geyelin delivered a talk to the American Medical Association on the therapeutic fasting in the treatment of epileptic seizures. In the UK, Professor Helen Cross led a medical trial that led to the diet’s adoption by the NHS as a treatment of children with drug-resistant epilepsy.

The Dietetics Association of Australia says that more research is required on the safety and efficacy of the diet, while Sports Dietitians Australia states that quality carbs are essential for athletes. Louise Burke, head of sports nutrition at the AIS, has written several articles about “Fat Adaptation” most recently in 2015, in which she maintains that a low-carb, high-fat diet drains energy by disrupting production of an enzyme called pyruvate dehydrogenase (PDH).

Others however point to the studies being flawed, mainly because the subjects’ fat-adaptation phases were as short as five days. That’s all very interesting. But let’s get to the crunch. Will a ketogenic diet make you a super ultra runner? Only time will tell! There are examples of elite ultra runners who are ketone-friendly and smash records, but there are just as many incredible runners who aren’t on the diet. Everybody is different, so the answer comes down to your individual body.

Nicki Letts
Nicki Letts and her partner Mat are trail runners and vanlifers, travelling around in their VW Kombi "The Old Girl" and hitting the trails at every opportunity. They ran their first 100km race back in 2011 and have been enjoying the view from the middle of the pack ever since. Follow their trail adventures at www.runoldgirlrun.com.au

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