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Keto for Triathletes?

keto for triathletes

Right now, keto is one of the most popular diets around. But does it work for athletes? 

Some people say that keto can help you lose weight and improve your performance, while others think that it’s not a good idea for endurance athletes. 

So what’s the truth? Is keto good for triathletes? Here’s what you need to know.


The Science of Keto 

First, a quick introduction to the ketogenic diet. This high-fat, low-carbohydrate way of eating forces your body to burn fat for fuel instead of carbohydrates

When you cut down on carbohydrates, your body doesn’t have enough glucose to use for energy. As a result, you enter the metabolic state of “ketosis” so the body can create an alternative source of energy. 

During ketosis, your liver produces molecules called “ketones” from stored fat. These ketones are then used by your muscles and brain for energy. 

Most people enter ketosis within 2-4 days after starting a ketogenic diet, but it can take 2-3 weeks for the body to fully adapt to using fat for fuel. 

For athletes considering using ketosis as a competitive advantage, it’s important to start the keto diet well ahead of important competitions to give your body time to adapt. PlanKetogenic’s guide for athletes is a good place to start in terms of learning which foods to eat or avoid on keto, how much protein to have, and other practical questions.

So, how can a low-carb diet benefit triathletes? Let’s take a look


Keto for Triathlon

There are three main ways that the keto diet can help you in a triathlon:

  1. providing more consistent energy levels (avoiding spikes and slumps)
  2. improving mental clarity
  3. reducing inflammation

First, let’s talk about energy levels. When you’re training for a triathlon, you need to be able to sustain long periods of activity without running out of steam. 

This can be difficult when relying on carbohydrates for fuel, as you need to carefully time your meals before your event. If you aren’t properly fueled up, glucose levels can drop quickly, leading to fatigue and brain fog. 

The keto diet solves this problem by providing a consistent source of energy from fat stores. With fatty acids readily available to be used as fuel, you may be able to train harder and longer without feeling worn down. 

In addition to increased energy levels, the keto diet has been shown to improve your mental clarity.1  When you’re in peak mental condition, you’ll be able to make better decisions about your race strategy and execute it flawlessly on race day. 

Finally, the keto diet can help reduce inflammation throughout the body. Inflammation is one of the leading causes of fatigue, pain, and stiffness in athletes.2

By reducing inflammation, the keto diet allows you to recover from triathlete training sessions more quickly and reduce your risk of injuries.

However, the research on keto diets and triathlon athletes is limited, so conclusive conclusions cannot be drawn. Each person’s body may react differently, so what works well for one athlete may not have the same effect on another.


Keto and endurance cycling

For years, cyclists have been told that a high-carb diet is essential for peak performance. But what if there was a way to get all the energy you need from fat? That’s the premise of the ketogenic, or “keto,” diet.

By dramatically reducing carbs and replacing them with fat, the keto diet forces your body to burn fat for fuel. This has a few potential benefits for endurance cyclists. 

First of all, it can assist you in losing weight.

In addition, it increases your stamina by teaching your body to burn fat more efficiently.

Furthermore, it may have a beneficial effect on recovery from workouts, since it reduces inflammation.

Recent studies have also shown that a ketogenic diet can improve exercise performance and metabolism.

In one study, cyclists who followed a ketogenic diet for 4 weeks showed improved power output and VO2 max (a measure of oxygen uptake) compared to those who followed a high-carbohydrate diet.3 

Despite these studies, it has not been definitively established that low-carb or ketogenic diets are effective in improving endurance at high intensity.

Of course, the keto diet isn’t right for everyone. It takes time to adjust to burning fat for fuel, and some people find it difficult to stick to such a strict diet. 

But if you are willing to give it a try, and see what effect it has on your endurance, you may get good results.


Endurance running on a keto diet

So why would an endurance runner want to switch to a keto diet? The answer lies in how our bodies use different fuels during exercise. 

When we start exercising at a moderate intensity, our bodies burn a mix of fatty acids (FAs) and glucose (a simple sugar molecule). 

However, as we start to exercise harder, our bodies begin to rely more and more on glucose for fuel. 

The problem is that we have a limited supply of glucose stored in our muscles in the form of glycogen. Once that glycogen is gone, we hit “the wall” and our performance plummets.

On a keto diet, however, our bodies become incredibly efficient at burning FAs for fuel. This means that we can exercise at higher intensities for longer periods of time before hitting “the wall.” 

So theoretically for endurance runners, this can be a game-changer. Not only can it allow them to train harder and longer, but it may also enable them to race at speeds they never thought possible.

This theory, however, is still limited by research, which makes it challenging to make any definitive statements. More research is needed to determine whether or not the ketogenic diet offers any real advantages for endurance athletes. 

If you are considering trying a ketogenic diet, it is important to speak with a doctor or registered dietitian first to ensure that it is safe for you and to create a plan that will meet your individual needs. 

Of course, switching to a keto diet isn’t easy. It takes weeks or even months for the body to fully adapt to using FAs for fuel. And during that adaptation period, many athletes experience side effects like brain fog and irritability. 

However, those side effects generally subside once adaptation is complete. For dedicated endurance runners who are willing to put in the work, a properly planned keto diet may be worth trying out.


Swimming and low-carb diets

The body’s primary source of fuel during exercise is glycogen, which is stored in the muscles and liver. Glycogen is a complex carbohydrate that is broken down and converted to glucose, which the body then uses for energy. 

When glycogen stores are depleted, athletes “hit the wall” or “bonk”, which can lead to a significant decrease in performance.

For this reason, many athletes focus on loading up on carbohydrates in the days leading up to an event in order to maximize their glycogen stores. 

However, recent research has suggested that a low carbohydrate diet may actually be more beneficial for endurance athletes like swimmers.

Theoretically, low-carb diets may be beneficial for swimmers in a number of ways. One theory is that low-carb diets help to spare glycogen, which is a stored form of carbohydrates in the muscles. 

When glycogen stores are depleted, swimmers’ muscles tire and they lose their strength and power. 

By following a low-carb diet, swimmers can help to preserve their glycogen stores and swim for longer periods of time without tiring. 

Another advantage of low-carb diets for swimmers is that they can help with weight loss.4 Most competitive swimmers need to be within a certain weight range in order to compete at their best. 

If you are carrying extra weight, it can drag you down in the water and make it more difficult to swim fast. Following a low-carb diet may help you to shed any excess fat and improve your swim times.


Implementing a Low-Carb Diet

If you’re interested in trying a low-carb diet to improve your swimming performance, there are a few things to keep in mind. 

First, while a low-carb diet can help you burn more fat during exercise, it’s important to make sure you’re still eating enough total calories to meet your energy needs.

Second, because carbohydrates are the primary fuel source for high-intensity exercise, it’s important to monitor your training when first implementing a low-carb diet carefully. 

You may need to adjust your training volume or intensity until your body becomes more efficient at using fat as fuel. Working with a coach can help ensure you’re still able to safely train while following a low-carb diet. 


Is Keto Good for Endurance Athletes?

Let’s see what the science says about keto and endurance training.

There is some evidence to suggest that the ketogenic diet can improve performance in endurance events. One study found that cyclists who were on a ketogenic diet could ride longer than those who weren’t on the diet. 

However, it’s worth noting that this study was done on trained cyclists; it’s not clear if the same would be true for untrained individuals or those competing in other endurance sports. 

It’s also important to keep in mind that going into ketosis takes time—usually 2-4 days. 

This means that if you’re an athlete who is trying out the ketogenic diet, you might not have enough time to get into ketosis before your event. 

As a result, you might not reap the benefits of the diet during competition. 

If you’re an athlete who is thinking about trying out the ketogenic diet, make sure you give yourself enough time to enter into ketosis before your competition so that you can see how your body responds.

Overall, the research on whether the ketogenic diet is good for endurance athletes is inconclusive. 

There is some evidence to suggest that the diet can improve performance, but more research needs to be done in this area—particularly on untrained individuals and those competing in different types of endurance events. 


Keto Snacks for Endurance Athletes

If you do decide to give keto a try, here are some low-carb snacks to help you stay energized.

Almonds – Almonds are a great source of healthy fats, protein, and fiber. They’re also easy to transport and make a great pre-workout snack. Simply throw a handful in a ziplock bag and you’re good to go.

Hard-boiled eggs They are another great source of protein and healthy fats. They’re also incredibly versatile – you can eat them plain or add them to a salad or wrap. And they’re easy to prepare ahead of time, so you can grab them and go when it’s time for your workout.

Homemade protein bars – Store-bought energy bars can be full of sugar and other additives that you don’t need. Instead, try making your own at home using a recipe like this one from The Big Man’s World.  

Coconut chips – They are a delicious and nutritious way to fuel your workout. They’re packed with healthy fats and electrolytes, which are important for marathon runners and other endurance athletes. 

You can find coconut chips at most health food stores or make your own at home. 

Canned tuna – This is a great source of protein and healthy omega-3 fatty acids. It’s also very portable—just throw a can in your bag and you’re good to go. Be sure to choose tuna packed in water rather than oil for the healthiest option possible.

Cauliflower hummus – This dish is not only extremely easy to make but also packed with nutrients that will give you lasting energy. Cauliflower is a great source of fiber and antioxidants, both of which are important for gut health and staving off hunger. 

Chickpeas, the main ingredient in traditional hummus, are also high in fiber and protein, making this snack a great option if you’re looking for something to tide you over until your next meal. 

Zucchini chips – These chips are the perfect option if you’re craving something crunchy. Zucchini is a low-carbohydrate vegetable that is also high in vitamins A and C, two essential nutrients for immune health.

When choosing a dipping sauce, go for something with healthy fats like an avocado or olive oil-based dip to further increase ketone production and help you feel fuller longer. 

Coconut yogurt – If you’re looking for a snack that’s high in fat but low in carbohydrates, look no further than coconut yogurt. Coconut yogurt is made from coconut milk instead of cow’s milk, making it dairy-free and Paleo-friendly. 

It’s also rich in healthy saturated fats that will help keep you satiated until your next meal. Top with some fresh berries or nuts for an extra boost of flavor and nutrients.

Chocolate fat bombs – These little bites are perfect for when your sweet tooth strikes but you don’t want to compromise your ketogenic diet. 

Chocolate fat bombs are made with cocoa powder and coconut oil or butter and are an excellent source of healthy fats. 

Be sure to choose dark chocolate with at least 70% cacao content for the most health benefits. Store them in the fridge for when those afternoon cravings kick in! 

Protein powder – Protein supplements can be a valuable tool in getting adequate protein but maintaining ketosis. It’s critical to use very low-carb protein powders with less than 1 gram of sugar. See this post on the best keto protein powder products for more info.

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Head of Content at Better Triathlete | Website

Endurance athlete, professional off-road cyclist, and avid blogger, Tyler Tafelsky participates in long-course multisport and cycling events. Today, Tyler competes in ultra-distance cycling races at the professional level. Since starting Better Triathlete in 2014, he has been the head of content for the site's editorial team. Learn more about Tyler