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Keto Diet For Marathon Runners

on December 01, 2022

Are Ketogenic diets good for a marathon runner?

The ketogenic diet has become more popular over the last years, with famous people like Lebron James and Kim Kardashian having tried it to lose weight.
This diet is not new; it has been around since 1920 when it was used to help kids with epilepsy and those with extreme obesity, which is still true today. Recently there has been evidence of its effect on body weight, diabetes, and Alzheimer's.
But is it really a strategy that marathon runners can use?
I will tell you how fat works in our body and if it is helpful for these types of competitions.
Fat is a fuel essential for strength training; alongside carbohydrates and ingesting good fats, they are necessary to optimize our health.
The usage of fats as an energy source depends on many factors, such as the length and intensity of the exercise, the level and physique of the runner, their diet, and the ingestion of carbohydrates before and/or during training.
During a prolonged exercise, the use of fats will be prolonged once the carbohydrate reserves have been exhausted. Edwards, Margaria, and Dill (1934) observed a rate of oxidation of 1g/min after running for 6 hours in a row. Christensen and Hansen (1939) observed that fat could contribute up to 90% of energy use. The oxidation rate increased to 1.5g/min when a fatty meal was consumed.
The Ketogenic diet uses fats as the primary energy source. It drastically restricts carbohydrates, reaching up to less than 50% of the total daily calorie intake.
When incorporating these changes in how we eat, our body is obligated to use fat as the fuel source, leading to the generation of Ketone bodies. Some argue that such a substrate can be suitable for the muscle and could help generate changes.
The problem is that there is a lack of scientific evidence concerning the functionality of this type of diet for resistance athletes. The only study that analyzed this was by Phinney, Bistrian, Evans, et al. (1983), which included five athletes trained in resistance sports and did not observe any benefit regarding their performance. However, they saw an improvement in how they metabolized certain fats.
Furthermore, another problem with this type of diet is that it becomes challenging to sustain over a long period. The process one goes through until it adapts to living in ketosis can be very uncomfortable and produce changes in cholesterol and triglyceride levels.
Another problem is that if your goal is to lower your time in your next marathon, this will not be a good strategy for you since you will definitely need a good amount of carbohydrates, or the body will not be able to respond appropriately unless you already have a reasonable amount of time practicing these changes so your body can be more efficient in its fat usage.
The good side of this diet is that it does help you be more conscious of the amount of sugar you consume, both in refined and processed foods. Therefore, it leads you to choose better quality meals.
What you can do is make use of the advantages of both types of diets. If you undergo low-intensity training, then you can reduce your consumption of carbohydrates or limit them during a race to make use of the changes this makes in your muscles.
Similarly, you consume a diet high in carbohydrates when the speed and intensity of the run require it. This is called nutrition periodization. It should be used alongside a professional who can advise you and make it as personalized as possible.
To summarise, the Ketogenic diet can make you more aware of what you eat each day in terms of quality and quantity, apart from helping you lower your weight if you do it for a long enough period and adapt it to your needs.
But suppose your goal is to improve your performance in sports and run faster. In that case, your carbohydrate intake must adapt to the type of exercise you will do in preparation for a marathon.
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