Keto Diet and Exercise: How Does It Affect Your Performance?

The keto diet is a low-carb, high-fat diet that aims to put your body into a state of ketosis, where it burns fat instead of glucose for energy. The keto diet has been shown to have various health benefits, such as weight loss, improved blood sugar control, reduced inflammation, and lower risk of chronic diseases . However, the keto diet also has some potential drawbacks, especially for exercise and athletic performance.

In this article, we will explore how the keto diet affects different types of exercise and athletic performance, and what factors to consider before adopting this diet. We will also share some tips on how to optimize your exercise performance while on the keto diet.

How does the keto diet affect different types of exercise?

The keto diet affects different types of exercise in different ways, depending on the intensity, duration, and frequency of the exercise, as well as the individual’s adaptation to ketosis. Some of the effects are:

• Reduced endurance performance: Endurance performance refers to the ability to sustain moderate to high-intensity exercise for a long period of time, such as running, cycling, or swimming. Endurance performance relies mainly on carbohydrates as the primary source of fuel, as they can be quickly and efficiently converted into glucose and used by the muscles. The keto diet limits the intake of carbohydrates and depletes the glycogen stores in the muscles and liver, which are the stored forms of glucose. This can impair the endurance performance, as the muscles may run out of fuel and fatigue faster .
• Improved fat-burning capacity: Fat-burning capacity refers to the ability to use fat as an alternative source of fuel when carbohydrates are scarce or unavailable. Fat-burning capacity relies mainly on fat oxidation, which is the process of breaking down fat into fatty acids and ketones, which can be used by the muscles and brain. The keto diet increases the fat oxidation rate and stimulates the production and utilization of ketones, which are energy molecules derived from fat. This can improve the fat-burning capacity, as the body can use more fat for energy and spare glycogen .
• Mixed effects on strength and power performance: Strength and power performance refer to the ability to generate force and speed in a short period of time, such as lifting weights, sprinting, or jumping. Strength and power performance rely mainly on creatine phosphate (CP), which is a high-energy molecule that can be rapidly used by the muscles. The keto diet does not affect the CP levels in the muscles, but it may affect other factors that influence strength and power performance, such as muscle mass, hydration status, electrolyte balance, and hormone levels. The keto diet may reduce muscle mass by decreasing protein synthesis and increasing protein breakdown . The keto diet may also cause dehydration and electrolyte imbalance by increasing water loss through urine and sweat and reducing intake of electrolyte-rich foods . The keto diet may also alter hormone levels by affecting insulin, testosterone, growth hormone, and cortisol levels . These effects may vary depending on the individual’s adaptation to ketosis, the type and intensity of exercise, and the timing and composition of meals .

What factors to consider before adopting the keto diet for exercise?

Before adopting the keto diet for exercise, there are some factors to consider, such as:

• Your goals: You should consider your goals for exercise and athletic performance, and whether they are compatible with the keto diet. If your goal is to improve your endurance performance or lose weight, you may benefit from the keto diet. However, if your goal is to improve your strength or power performance or gain muscle mass, you may not benefit from or even harm your performance by following the keto diet.
• Your adaptation: You should consider your adaptation to ketosis, which is the metabolic state where your body uses fat and ketones for energy instead of glucose. Adaptation to ketosis can take several weeks or months, depending on your individual factors such as genetics, metabolism, activity level, and dietary intake. During this period, you may experience some side effects such as fatigue, headache, nausea, constipation, bad breath, and reduced exercise performance . These side effects may subside as your body becomes more efficient at using fat and ketones for energy . However, some people may not adapt well to ketosis and may not experience any benefits or even worsen their health and performance .
• Your nutrition: You should consider your nutrition while on the keto diet, which is very restrictive and may not provide adequate amounts of certain nutrients that are essential for health and performance. Some of the nutrients that may be lacking or deficient on the keto diet are carbohydrates, protein, fiber, vitamins, minerals, and antioxidants. You should ensure that you consume enough of these nutrients from high-quality and varied sources, such as eggs, meat, fish, cheese, nuts, seeds, oils, leafy greens, berries, and supplements. You should also monitor your hydration and electrolyte status, as the keto diet can cause increased water and electrolyte loss. You should drink plenty of water and consume electrolyte-rich foods or drinks, such as broth, pickle juice, coconut water, or sports drinks.

How to optimize your exercise performance while on the keto diet?

If you decide to follow the keto diet for exercise, there are some tips to optimize your exercise performance, such as:

• Choose the right type of exercise: You should choose the type of exercise that suits your goals and matches your metabolic state. If you are on the keto diet, you may perform better on low-intensity and long-duration exercises that rely more on fat oxidation, such as walking, jogging, cycling, or swimming . However, you may perform worse on high-intensity and short-duration exercises that rely more on glycogen, such as sprinting, weight lifting, or interval training . If you want to do these types of exercises, you may need to modify your keto diet by increasing your carbohydrate intake before or after exercise to replenish your glycogen stores and enhance your recovery .
• Time your meals: You should time your meals according to your exercise schedule and intensity. If you are on the keto diet, you may benefit from eating a high-fat and moderate-protein meal about 2 to 4 hours before exercise, as this can provide enough energy and prevent hunger during exercise. However, if you are doing a high-intensity or long-duration exercise, you may benefit from eating a small amount of carbohydrates about 30 to 60 minutes before exercise, as this can boost your performance and prevent fatigue during exercise. You should also eat a high-protein and moderate-carbohydrate meal within 2 hours after exercise, as this can promote muscle protein synthesis and glycogen replenishment.
• Supplement wisely: You should supplement wisely while on the keto diet, as some supplements may enhance or impair your exercise performance. Some of the supplements that may enhance your performance are creatine, caffeine, beta-alanine, and branched-chain amino acids (BCAAs) . These supplements can increase your muscle strength, power, endurance, and recovery . However, some of the supplements that may impair your performance are exogenous ketones, medium-chain triglycerides (MCTs) , and raspberry ketones . These supplements can interfere with your natural ketone production and utilization and cause gastrointestinal distress .

Conclusion

In conclusion, the keto diet affects exercise and athletic performance in different ways, depending on the type, intensity, duration, and frequency of exercise, as well as the individual’s adaptation to ketosis. The keto diet may improve low-intensity and long-duration exercises that rely on fat oxidation, but impair high-intensity and short-duration exercises that rely on glycogen. The keto diet may also affect other factors that influence exercise performance, such as muscle mass, hydration status, electrolyte balance, and hormone levels. Before adopting the keto diet for exercise, you should consider your goals, adaptation, and nutrition. You should also follow some tips to optimize your exercise performance while on the keto diet.