Should Strength Athletes Use The Keto Diet? (Science-Backed)

 


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There’s no doubt about it — keto has captured the attention of the nutrition world.  

Even athletes are using this very low carbohydrate and high-fat diet, which has been associated with rapid fat burn, appetite control, and other health advantages. 

However, carbohydrates have long been considered the finest fuel for fitness and strength building.  So cutting an entire food group has some athletes, coaches, and medical professionals (myself included) concerned about the detrimental effects of this very low carbohydrate diet on strength performance.  

So, should strength athletes use the keto diet?

When first switching to a keto diet, some people may have decreased strength performance. But once the body adapts, building strength comes down to consuming a caloric surplus (eating more than you burn), eating enough protein (1 to 1.5 grams per pound bodyweight), and doing regular strength training (two to three times per week).

Let’s dive into the research around carbs versus high fat for strength athletes. 


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What Is The Keto Diet?

 


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Keto is short for the ketogenic diet. This eating style consists of eating high fat, moderate protein, and very low carbohydrates. Daily macronutrients are divided into the following percentages:

  • Carbohydrates: 5-10%

  • Protein: 30-35%

  • Fat: 55-60%

The ketogenic diet was originally developed as a way to treat epilepsy. It’s since had a recent resurgence as a way to lose weight rapidly. It’s been shown to be quite effective in the short term, but long term results vary. 

How Does The Keto Diet Work For Athletes?

Glucose is the primary source of energy for the brain and muscles. It’s usually obtained from foods that are rich in carbohydrates (bread, pasta, grains, fruits) then used as fuel or stored as glycogen in the liver and muscles for later use. 

When there isn’t enough glucose provided by food (less than 50 grams per day), and all the storage forms have been used, the body has to switch to a fat burning state. By breaking down fat stores, your body can get energy from triglycerides and ketone bodies. 

Ketones are actually acids, in small amounts they indicate the body is breaking down fats but in high levels they can poison the body, called ketoacidosis. The nutritional ketosis state is considered safe because the ketone bodies are produced in small amounts without changing the pH level (acid versus base) of the blood. 

Ketone body production depends on factors such as basal metabolic rate, body weight, and body fat percentage. A healthy adult can usually enter ketosis in about three to four days. You can also get to a state of ketosis faster through intense exercise such as high-intensity-interval training (HIIT). 

What Can You Eat On A Keto Diet If You’re An Athlete?

To follow a keto diet, you’ll have to give up sweets and carbs and go for higher-fat foods like nuts, seeds, oils, eggs, cheese, butter, and meats. Then focus on fibrous, lower carb vegetables like asparagus, broccoli, leafy greens, and bell peppers. 

Higher carb vegetables should be minimized or avoided such as pumpkin, potatoes, squash, carrots, and corn. Fruit should be skipped or at least limited since it’s higher in natural sugar.

Here are some examples of healthy, keto friendly foods:

  • FATS: avocado, plant-based oils (coconut, olive, flax), butter

  • PROTEIN: eggs, beef, poultry (chiken, turkey), fish, plain greek yogurt

  • SOME CARBS: leafy greens (spinach, kale), brussels sprouts, onion, broccoli, berries

Benefits Of Keto For Athletes

 


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The most commonly known benefits of the keto diet are weight loss, appetite control, improvements in health factors such as blood cholesterol, and brain support. 

During ketosis, inulin levels go down. Insulin is a hormone that helps bring glucose (energy from carb foods) into your cells, muscles, and liver and to be used for energy. However, when insulin stays chronically high, it can lead to more fat being stored, blood sugar concerns, and increased risk for heart disease. 

A review of studies done on animals and humans found that some people showed a significant decrease in total cholesterol and “bad” cholesterol (LDL) while increasing “good” cholesterol (HDL). Some research has also shown that the keto diet can help benefit the brain by protecting nerve cells. 

Harvard Health highlights how previous research shows good evidence of faster weight loss when patients are on the ketogenic diet versus traditional low-fat diet or Mediterranean diet, but the difference in weight loss seems to even out overtime.

Concerns About Keto For Athletes

It’s important to note that the benefits of keto have been well reported and established in the short-term (up to 2 years) but the long-term health effects are not well known due to limited research. 

The most common short-term effects include nausea, vomiting, fatigue, insomnia, dizziness, constipation, and difficulty with exercise. These symptoms are typically referred to as the “keto flu” and usually last a few days to a few weeks. Making sure to stay hydrated with fluids and electrolytes can help. 

The long-term dangers include fatty liver, low protein, kidney stones, and vitamin and mineral deficiencies. Health experts do agree that the keto diet can be potentially dangerous for people with a medical condition or a history of disordered eating, including yo-yo dieting. 

As Harvard Health explains, since carbohydrates usually make up at least 50% of the typical American diet, it can be very challenging to follow this diet in the long-term. People may also feel tired at the beginning, and experience bad breath, nausea, constipation and sleep problems. 


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Should Strength Athletes Use The Keto Diet? (What to Consider)

 


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Current research suggests that it’s possible to strength train, build muscle, and improve strength on the keto diet when compared to a higher carb diet. 

EVERYONE ADAPTS DIFFERENTLY 

Some people may experience negative symptoms during the first couple weeks of transitioning to a keto diet such as nausea, headaches, fatigue, and flu-like symptoms. This may also impact your fitness and energy levels. Be patient and make sure to listen to your body during this time.

Yet this isn’t the case for everyone. One study done on gymnasts tested fitness levels before and after a 30 day modified ketogenic diet. They found no significant differences between the keto diet and regular diet for the strength tests, but body weight and fat mass decreased in the keto dieters. 

LOW CARB STILL STIMULATES STRENGTH   

   

Many leading health authorities such as the American College of Sports Medicine (ACSM) and the American Council on Exercise (ACE) recommend for general good health to aim for 45%-65% of daily calories from carbohydrates. Athletes who participate in high-intensity sports may need to get closer to 60% to 70% carbohydrates. 

It was previously thought that it was impossible to build muscle on low carb diets because the fact that insulin brings glucose into cells which helps with muscle growth. But recent studies suggest that it is possible to gain and build muscle and strength on the keto diet.

In one study, college age men were divided into a keto diet or traditional western diet and trained for 11 weeks. As a result, the keto diet in combination with resistance training lead to favorable change in body composition, performance, and hormonal profiles in the resistance-trained men. 

In another study, untrained overweight women between 20 and 40 years old, completed a 10 week resistance training in combination with either a regular diet, low carb diet, or ketogenic diet. The resistance exercise in combination with a ketogenic diet may reduce body fat without significantly changing lean body mass. 

Keep Count of Carbs

In order to reach a state of ketosis, it’s essential to cut carbs. Aim for about 5-10% of your total calories from carbohydrates. For a 2,000 kcal per day diet, the carbohydrates equal about 20 to 50 grams per day. 

To give you an idea of how quickly carbs add up on the keto diet, eating the equivalent of about ½ cup white rice, one slice of bread, or one small potato would add up to 20 grams of carbohydrates per day. This is the lower end of the 20 to 50 gram recommendation for a 2,000 kcal diet.

PAY ATTENTION TO PROTEIN 

On the keto diet, protein should make up about 20-25% of total daily caloric intake. Protein can actually kick you out of being in a state of ketosis. This is because when carbs are low, protein can be broken down into glucose. So the protein amino acids (building blocks) get converted from protein to sugar, which could prevent the body from making ketones. 

The International Society of Sports Nutrition found that for building and maintaining muscle mass, the overall daily protein intake should range from 0.64-0.90 gram per pound (1.4-2.0 g of protein per kilogram) of body weight per day. 

When it comes to keto requirements, studies have suggested that it’s safe to eat about 1 gram of protein per pound (2.2 grams per kilogram) of body weight for general activity, while athletes and people performing heavy exercise with weight training can increase protein intake to 1.5 grams per pound of body weight. 

Learn more about building muscle here: The Powerlifting Diet: Eating For Strength (Definitive Guide)

CONSUME ENOUGH CALORIES 

Alongside protein and a well planned out weight lifting routine, consuming a calorie surplus (taking in more than you burn) is essential for muscle building. During most training periods, a caloric intake of about 15% above your basal metabolic rate should be good.

Your basal metabolic rate (BMR) is the minimum number of calories needed to do basic functions such as breathing, circulation, nutrient breakdown, and cell production, at rest. A good way to determine this is to use a calorie calculator such as the Harris-Benedict formula.

Calculating your energy balance

 


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According to Mayo Clinic, about 3,500 calories is equal to about a pound. This could change with consideration of someone’s age, sex, activity level, and physiology including hormones and gut bacteria. But whether or not you’re on keto, if you add about 500 to 1,000 calories per day, you’ll be on your way to gaining about one to two pounds per week. 

Final Thoughts

It’s not certain if the keto diet provides more benefit to strength performance and muscle build when compared to higher carb diets. But the current research suggests that as long as you focus on getting enough calories and protein, you should still be able to strength train. 

Before considering a keto diet, keep in mind that it can be challenging to follow and requires a lot of planning ahead as well as carefully monitoring your macronutrient balance. 

Whether you’re on the keto, higher carb, or other diet, it’s important to pay attention to how your body feels. Focus on natural food sources versus the more processed stuff as much as possible. And always consult a physician or medical provider before trying a new diet or fitness plan.


About The Author

 


Lisa Booth

Lisa Booth

 

Lisa is a registered dietitian nutritionist (RDN) with over 15 years of experience in nutrition, fitness, and mental health coaching and education. She studied Foods and Nutrition at San Diego State University and earned a Master of Science in Holistic Nutrition at Hawthorn University.

Having certifications and experience in group exercise, intuitive eating, coaching and psychotherapy, and digestive wellness, she’s enthusiastic about the relationship between the body and mind.

She’s dedicated to helping people understand how to implement healthy habit change, while gaining a deeper understanding of what makes them feel their personal best.