Exercise And Keto: Should You Work Out In Ketosis?

The ketogenic diet is a low-carb, high-fat, moderate-protein diet that has been linked to a long list of potential health benefits, including weight loss, improved blood sugar control, and decreased hunger levels. However, its effect on athletic performance remains controversial. While some claim that keto can boost fat burning and enhance endurance, others argue that it could drain energy levels and impair muscle growth. So, should you exercise when starting keto?

Well, it depends. Combining keto with exercise can maximize weight loss results, increase muscle mass, and provide a long-lasting energy boost. However, it is important to listen to your body and adjust your workouts accordingly. When starting keto, the body goes through a significant metabolic adjustment, switching from burning glucose to burning fat as its primary fuel source. This transition can lead to symptoms such as exhaustion, brain fog, muscle cramping, and irritability, commonly known as the keto flu.

To minimize the impact of the keto flu, it is recommended to focus on lower-intensity workouts during the initial phase of the keto diet. Low-intensity, steady-state exercises such as jogging, cycling, yoga, and strength training are generally well-suited for keto dieters. High-intensity exercises like HIIT, CrossFit, or heavy weight lifting may be more challenging due to the body's reliance on glucose for fuel during these activities.

Additionally, it is crucial to ensure adequate calorie and nutrient intake, especially consuming enough healthy fats. Proper fueling is essential to support your workouts and promote optimal muscle recovery. Overall, combining keto with exercise can be beneficial, but it is important to tailor your workout routine and dietary approach to your individual needs and fitness goals.

High-intensity exercise and keto

High-intensity exercises, such as sprinting, boxing, swimming laps, or jumping rope, are fuelled by carbohydrates. Therefore, the keto diet, which is low-carb and high-fat, may not be suitable for these types of activities.

The keto diet can negatively affect athletic performance and energy levels, especially when your body is first adapting to using fat for fuel instead of carbs. During this initial adjustment period, you may experience what is known as the "keto flu", which involves flu-like grogginess and stomach upsets. It is recommended that you do not try a new workout during the first few weeks of starting keto.

High-intensity exercises are fuelled by glycogen, which is derived from carbohydrates. When you restrict your carb intake, your body will have less glycogen available, which can impact your performance during high-intensity workouts.

However, it is important to note that some people who engage in high-intensity sports such as Crossfit and Obstacle Course Racing have found success with the keto diet. Additionally, studies have shown that repeated sprinting, a high-intensity activity, can quickly lower glycogen stores, which may be beneficial for those on a keto diet.

To perform high-intensity exercises while on the keto diet, it is crucial to reach a fat-adapted state. This involves consistently keeping your carb intake low, so your body becomes more efficient at burning fat for fuel. It is also recommended to consume enough fat to compensate for the lack of carbs, as this will help you feel more energised and maximise the benefits of the keto diet.

Low-intensity exercise and keto

The ketogenic diet is a very low-carb, high-fat, and moderate-protein diet that is designed to put the body in a state of ketosis, where it burns fat as a fuel source instead of carbohydrates. While the keto diet is popular for its weight loss benefits, it is unclear whether it has any advantages for exercise.

Low-intensity, steady-state exercises like jogging, cycling, rowing, and yoga are generally the least affected by the keto diet. This is because they are powered by the body's ability to use fat as an alternative energy source, which is enhanced when the body is in ketosis.

Some studies have found that the keto diet may improve physical endurance, especially in endurance athletes. One study in 39 athletes found that being in a metabolic state of ketosis improved physical endurance. Another study in 20 endurance athletes reported improved performance, body composition, and fat burning during exercise after following a ketogenic diet for 12 weeks.

Additionally, the keto diet may also speed up muscle recovery. A small study in five athletes reported self-perceived improvements in recovery and inflammation after exercise. Another study in off-road cyclists found reduced levels of creatine kinase and lactate dehydrogenase, two enzymes used to measure muscle damage.

However, it is important to note that the keto diet may also decrease energy levels, especially when the body is first adapting to using fat for fuel instead of carbohydrates. This can negatively affect athletic performance, especially for high-intensity exercises.

Therefore, while the keto diet may have some benefits for low-intensity exercises, it is important to listen to your body and adjust your workouts accordingly.

The keto flu

Signs of the keto flu may start to appear within the first few days of cutting back on carbs, and they can last from a few days to several weeks. The symptoms range from mild to severe and vary from person to person.

The symptoms of the keto flu include:

• Headaches
• Foggy brain
• Fatigue
• Irritability
• Nausea
• Difficulty sleeping
• Constipation
• Diarrhea
• Muscle soreness
• Cravings

There are several ways to reduce the symptoms of the keto flu:

• Drink plenty of water
• Eat more frequently and include plenty of colourful vegetables
• Get enough sleep
• Avoid strenuous activities
• Eat enough fat and carbohydrates
• Replace electrolytes

Macronutrients and keto

The ketogenic diet is a high-fat, low-carb, and moderate-protein diet. The typical keto macro ratio is 70% fats, 5% carbohydrates, and 25% protein. However, some dietitians recommend increasing fat intake to 75% and reducing protein to 20%.

Fats

Fats are 90% ketogenic and only 10% anti-ketogenic. This means that significant amounts of fat can be consumed without impacting ketone levels. The glycerol from triglycerides can be converted into glucose, but this will have a negligible effect on ketosis.

Proteins

Proteins are roughly 46% ketogenic and 54% anti-ketogenic. Insulin levels usually rise in response to the absorption of specific amino acids, and insulin indirectly decreases ketone production. Therefore, consuming excessive amounts of protein can decrease ketone production and potentially kick you out of ketosis. It is important to consume enough protein to maintain or gain muscle mass without impairing ketone production.

Carbohydrates

Carbohydrates are 100% anti-ketogenic as they raise both blood glucose and insulin, triggering a decrease in ketone production. Carbohydrates have the most profound effect on ketosis out of all the macronutrients. When ingested, carbohydrates are metabolized first, regardless of how much fat or ketones are being burned. As a result, the amount of fat and ketones burned decreases as carbohydrate consumption increases.

To ensure that your daily food intake doesn't get in the way of ketone production, it is generally recommended to consume no more than 30 grams of carbohydrates per day.

Practical Applications

To achieve the desired macronutrient intake on the keto diet, it is important to use a keto calculator to determine your recommended macronutrient intake based on your body's needs. It is also helpful to use a calorie tracker to monitor your food intake and ensure you are staying within the recommended ranges.

Supplements for keto

The ketogenic diet restricts several food groups, so it's important to supplement with specific nutrients to ensure you're getting all the vitamins and minerals your body needs. Here are some supplements to consider when following a keto diet:

Magnesium

Magnesium is a mineral that boosts energy, regulates blood sugar levels, and supports the immune system. Many magnesium-rich foods like beans and fruits are high in carbs, so it may be challenging to meet your magnesium needs on a ketogenic diet. Taking a magnesium supplement can help reduce muscle cramps, difficulty sleeping, and irritability, which are common symptoms experienced during the transition to a ketogenic diet. Aim for 200-400 mg of magnesium per day.

Medium-Chain Triglycerides (MCTs)

MCTs are a popular supplement among keto dieters as they can quickly boost fat intake and increase ketone levels, helping you stay in ketosis. MCT oil, derived from coconut or palm oil, is a concentrated source of MCTs and can be easily added to shakes, smoothies, or taken by the spoonful. Start with a small dose (1 teaspoon or 5 ml) to see how your body reacts before increasing the amount.

Omega-3 Fatty Acids

Omega-3 fatty acid supplements such as fish or krill oil are rich in EPA and DHA, which have been found to reduce inflammation, lower the risk of heart disease, and prevent mental decline. They can also help maintain a healthy balance of omega-3 to omega-6 fatty acids when following a high-fat diet. Choose a reputable brand that provides at least a combined 500 mg of EPA and DHA per 1,000 mg serving.

Vitamin D

Vitamin D is important for several bodily functions, including facilitating calcium absorption, supporting the immune system, and promoting bone health. Vitamin D deficiency is common, so supplementing with this vitamin is generally recommended. Consult your doctor to determine if you're deficient and to prescribe the proper dosage.

Digestive Enzymes

The high-fat content of the ketogenic diet can be tough on the digestive system, causing unpleasant gastrointestinal symptoms like nausea and diarrhea. A digestive enzyme blend containing lipases (enzymes that break down fats) and proteases (enzymes that break down proteins) may help optimize digestion and reduce these side effects.

Exogenous Ketones

Exogenous ketone supplements are commonly used by those following a ketogenic diet to increase blood ketone levels and enhance athletic performance. They have also been linked to other benefits such as speeding up muscle recovery and decreasing appetite. However, research on exogenous ketones is limited, and they may not be necessary for all keto dieters.

Electrolyte Supplements

The transition to a ketogenic diet can result in increased water loss and a drop in sodium, potassium, and magnesium levels, leading to symptoms like headaches, muscle cramps, and fatigue (known as the "keto flu"). Adding an electrolyte supplement containing sodium, potassium, and magnesium can help prevent these unpleasant symptoms. Alternatively, increase your intake of sodium by salting your foods or sipping on broth, and consume more magnesium and potassium-rich foods such as dark leafy greens, nuts, avocados, and seeds.

Supplements for Athletic Performance

Athletes following a ketogenic diet may benefit from supplements that preserve muscle mass, boost performance, and prevent fatigue. Some options include creatine monohydrate, caffeine, branched-chain amino acids (BCAAs), HMB (beta-hydroxy beta-methylbutyrate), and beta-alanine. These supplements have been shown to promote muscle gain, improve exercise performance, increase strength, and reduce exercise-related muscle damage and soreness.

Frequently asked questions