Protein And Exercise On Keto: How Much Is Enough?

The ketogenic diet is a low-carb, high-fat, moderate-protein diet that has been linked to a long list of potential health benefits, ranging from improved blood sugar control to decreased hunger levels. However, its effect on athletic performance remains controversial. While some claim that keto can boost fat-burning and enhance endurance, others note that it could drain energy levels and make muscle growth more challenging.

The keto diet can be particularly challenging for those engaging in high-intensity exercises, as it limits the ability of muscle cells to access sugar, one of the fastest fuel sources that the body relies on. This can impair performance in activities such as weight lifting, sprinting, swimming, and high-intensity interval training.

To optimise the keto diet for exercise, it is crucial to consume adequate protein, as it improves satiation, stimulates muscle protein synthesis, and has a more significant thermic effect than other macronutrients. The recommended protein intake for athletes and regular exercisers is 1.4-2 grams per kilogram or 0.6-0.9 grams per pound of lean body mass.

Additionally, carb intake and timing play a crucial role in exercise performance on a keto diet. The targeted ketogenic diet involves consuming carbs immediately before working out, while the cyclical ketogenic diet involves cyclical periods of strict keto and carb refeeding.

Overall, combining keto with exercise requires careful planning to ensure adequate fuel for different types of activities while maximising the health benefits of the diet.

The keto diet and exercise performance

The ketogenic diet is a very low-carb, high-fat, moderate-protein diet that has been linked to a long list of potential health benefits, ranging from improved blood sugar control to decreased hunger levels. However, its effect on athletic performance remains a subject of controversy. While some claim that keto can boost fat burning and enhance endurance, others note that it could drain energy levels and make muscle growth more challenging.

The impact of keto on exercise performance

By restricting carbs, we limit our muscle cells' ability to access sugar (glucose) – one of the fastest fuel sources that the body relies on. When our muscles don't have enough sugar, their ability to function at high intensities is impaired. This typically happens during any activity that lasts longer than 10 seconds as the muscles start to rely on glucose for energy by using a metabolic pathway called glycolysis.

For this reason, any muscular activity that requires near-maximal to all-out effort for 10 seconds to about 120 seconds can only be fuelled by glucose. Fat and ketones cannot stand in for glucose in the glycolytic pathway. Only after around 2 minutes of exercise will your body start to shift to metabolic pathways that can burn ketones and fat.

This means that the ketogenic diet can limit your performance during high-intensity activities like:

• Lifting weights for >5 rep sets using a weight that is heavy enough to take you to failure (or close to it)
• Sprinting or swimming for longer than 10 seconds (e.g., 100-metre sprint or 50-metre freestyle swim)
• Playing sports with minimal rest breaks like soccer, rugby, and lacrosse
• High-intensity interval training or circuit training

However, the timing of each metabolic pathway depends on the person. Some may be able to maintain their performance for high-intensity efforts that last longer than 30 seconds without burning carbs, while others may burn out after 10 seconds of all-out effort.

Eating the right quantity of macronutrients while exercising on keto

When creating a diet plan for active individuals, many health professionals prioritise protein intake. This is because protein performs many actions that carbs and fats cannot emulate. For example, protein improves satiation, stimulates muscle protein synthesis (muscle building), and has a more significant thermic effect (more calorie burning) than any other macronutrient.

The most recent International Society of Sports Nutrition position stand on diets and body composition reported that a protein intake of 1.4-2 g per kilogram or 0.6-0.9 grams per pound of lean body mass is ideal for athletes and others who exercise regularly. If you are highly active and/or trying to lose weight, you may benefit from eating around 2.2 grams of protein per kilogram of lean body mass (1 gram of protein per pound of lean body mass).

Keto athletes will also benefit from higher protein intakes because their bodies will use the excess protein to provide their muscles with the glucose they need through a process called gluconeogenesis. However, if your goal is to get into deeper levels of ketosis, it is best to divide your protein intake evenly between meals while eating a bit more protein after your workout to boost recovery without impairing ketone production.

The best protein sources on the ketogenic diet:

• Low-carb protein powders
• Meat
• Eggs and high-fat dairy
• Nuts and seeds
• Seafood
• Poultry

The bottom line

The ketogenic diet is not the ideal diet for high-intensity activities, but it is ideal for weight loss, reversing many chronic diseases, and improving our health in many ways. To combine exercise and keto, we must make changes to our diet and workout program to accommodate the effect that carbohydrate restriction has on physical performance.

The impact of keto on different sports

The ketogenic diet is a very low-carb, high-fat, moderate-protein diet that has been linked to a long list of potential health benefits, ranging from improved blood sugar control to decreased hunger levels. However, its effect on athletic performance remains controversial. While some claim that keto can boost fat burning and enhance endurance, others note that it could drain energy levels and make muscle growth more challenging.

High-Intensity Sports

The ketogenic diet may not be suitable for high-intensity sports, as the majority of high-intensity exercises are powered by carbohydrates. The human body stores carbohydrates in the muscle cells as muscle glycogen, which becomes an immediate fuel source for the body during high-intensity movements, including strength training, sprinting, and other sports. As the body burns fat for energy rather than carbohydrates on a keto diet, the process is overall less efficient, which may result in decreased performance during high-intensity workouts.

Low-Intensity Sports

Low-intensity, steady-state workouts (like easy jogging or cycling) tend to be the least affected by the keto diet. The diet may even enhance performance for endurance athletes, as it improves physical endurance due to the body's ability to use fat as an alternative source of energy. Additionally, the keto diet may speed up post-workout muscle recovery and increase fat burning during exercise.

Sports Requiring Short Bursts of Energy

Keto may not be the best diet for sports that require short bursts of energy, such as weightlifting or sprinting. The diet can decrease energy levels, especially during the initial stages of adaptation, and impair muscle growth due to restricted protein intake.

How to eat keto for exercise

Exercising on a keto diet can be beneficial for losing weight and improving health, but it's important to understand how your body responds to this diet when working out. When you restrict carbohydrates, you limit your muscle cells' access to sugar, which is one of the fastest fuel sources for the body. This can impair high-intensity activities that rely on glycolysis, such as weightlifting, sprinting, and high-intensity interval training. However, keto can enhance endurance and fat-burning during steady-state aerobic exercises like distance running or cycling.

Macronutrient Recommendations for Keto and Exercise:

• Protein: Aim for 1.2-2.0 grams of protein per kilogram of body weight. This range can be adjusted based on your activity level and goals. If you're highly active and trying to lose weight, consider 2.2 grams per kilogram of lean body mass. For muscle gain, aim for at least 1 gram per pound of body weight.
• Carbohydrates: Start with a maximum of 35 grams of carbs per day. If your exercises rely on high-intensity activities, you may benefit from increasing your carb limit, implementing a Targeted Ketogenic Diet (TKD), or following a Cyclical Ketogenic Diet (CKD).
• Fat: Adjust your fat intake based on your goals. For muscle gain, aim for a calorie surplus of 250-500 calories, mostly from fat. For fat loss, create a calorie deficit of 250-500 calories by reducing fat intake.

Keto-Friendly Protein Sources:

• Meat: Grass-fed beef, chicken, pork, etc.
• Eggs: Chicken, quail, duck, etc.
• Dairy: Cheese, plain Greek yogurt, cottage cheese
• Low-carb protein powders
• Nuts and seeds: Peanuts, hazelnuts, macadamia nuts, walnuts, chia seeds, etc.

Tips for Combining Keto and Exercise:

• Cardio: Keto is well-suited for moderate-intensity cardio exercises like jogging, swimming, and cycling. Aim for a heart rate between 50-70% of your maximum heart rate. As you adapt to keto, you may be able to maintain a higher heart rate for longer.
• Weight Training: Focus on short, intense sets of fewer than 10 seconds per exercise to utilise the phosphagen system. If you prefer higher reps, consider a TKD or CKD approach to fuel your workouts.
• Endurance Training: For endurance sports, follow the general keto guidelines for fat, protein, and a lower carb intake. Gradually increase your carb intake above 35 grams per day if needed to match your pre-keto performance levels.

Macronutrients for exercise

The body is a complex machine that can adapt to a variety of situations and stresses, from sedentary activities to intense physical exertion. To function effectively, it requires a combination of macronutrients – protein, carbohydrates, and fats. Here's a guide to optimising your macronutrient intake for exercise, especially when following a ketogenic diet.

Protein

Protein is essential for muscle repair, growth, and the creation of hormones and enzymes. When exercising, it is crucial to consume adequate protein to support muscle recovery and growth. The recommended intake for athletes and individuals who exercise regularly is between 1.4 and 2 grams of protein per kilogram of body weight, or 0.6 to 0.9 grams per pound. This can be obtained from animal sources such as meat, poultry, seafood, eggs, and dairy, as well as plant-based sources like tofu, nuts, and seeds.

Carbohydrates

Carbohydrates are the body's primary fuel source during moderate to high-intensity exercise. However, on a ketogenic diet, carbohydrate intake is restricted, which can impact performance in activities lasting longer than 10 seconds. For endurance-type exercises like long-distance running, cycling, or swimming, fat becomes the main fuel source, and the body's ability to utilise fat for energy improves over time.

Fats

Fats are the predominant source of energy on a ketogenic diet, comprising around 70% of daily calories. It is important to adjust fat intake based on your goals. For weight loss, create a calorie deficit by reducing fat consumption, while for muscle gain, increase fat intake to create a calorie surplus.

Putting it all Together

To optimise your diet for exercise and ketosis:

• Calculate your protein requirements based on your weight, activity level, and goals.
• Adjust your fat intake according to your goals – create a deficit for weight loss or a surplus for muscle gain.
• Monitor your carbohydrate intake and consider implementing a targeted or cyclical ketogenic diet if you engage in high-intensity exercises.
• Ensure you are meeting your overall calorie needs for weight maintenance or desired weight change.

Cardio on a keto diet

The keto diet is a popular choice for those looking to lose weight, increase energy, and experience fewer blood sugar swings. However, its impact on exercise performance is less clear. While some claim that keto can boost fat burning and enhance endurance, others argue that it could drain energy levels and make high-intensity workouts more challenging.

The Benefits of Keto for Cardio

• Fat Burning: The keto diet may help increase fat burning during aerobic exercise such as distance running or cycling. This is because the body is using fat, instead of carbohydrates, as its primary fuel source.
• Endurance: Some studies suggest that keto may improve physical endurance due to the body's ability to use fat as an alternative energy source. However, this effect was observed with the use of ketone supplements rather than through the diet alone.
• Muscle Recovery: The keto diet could help speed up post-workout muscle recovery and reduce protein breakdown. This may be especially beneficial for endurance athletes.

The Challenges of Keto for Cardio

• High-Intensity Workouts: The keto diet may impair performance during high-intensity exercises such as strength training, sprinting, and other sports. This is because carbohydrates are the main fuel source for these types of activities, and keto restricts carbohydrate intake.
• Energy Levels: Switching to a keto diet can lead to decreased energy levels, especially during the initial adaptation phase when the body is learning to use fat for fuel instead of carbohydrates.
• Muscle Growth: Maximizing muscle growth may be challenging on a keto diet as it often involves restricting calorie and protein intake, both of which are important for muscle synthesis and repair.

Recommendations for Cardio on Keto

• Low-Intensity Steady-State (LISS) Cardio: Opt for low-intensity exercises such as walking, jogging, cycling, swimming, or yoga. These activities are less likely to be affected by the keto diet and are more sustainable for beginners or those new to keto.
• Moderate-Intensity Exercise: Some studies suggest that keto, combined with moderate-intensity exercise, can positively impact body composition and maximize weight loss efforts.
• High-Intensity Interval Training (HIIT): If you want to incorporate HIIT into your routine, aim for a fat-adapted state. This means consistently keeping your carb intake low (30-50 grams per day) for several weeks to help your body burn fat more effectively.
• Sleep and Recovery: Prioritize adequate sleep (at least 7 hours) as it affects your energy levels, appetite, and motivation to exercise.
• Nutrition: Ensure you are eating enough calories and getting sufficient protein, especially if you are engaging in resistance training or endurance-type exercises. Consult with a healthcare professional or nutritionist to determine your individual needs.

Frequently asked questions