Keto Workout Duration: How Long To Exercise Effectively?

The ketogenic diet is a popular choice for those looking to lose weight and improve their health. But what happens when you combine keto with exercise? Does it affect performance? And will exercise make avoiding carbs impossible?

Exercising on a keto diet is perfectly possible, but it's important to understand that your body will respond differently as it adjusts to a new way of fuelling itself. The keto diet involves severely restricting carb intake, which are the body's main source of energy. As a result, switching to keto can impact athletic performance and energy levels, especially during high-intensity workouts.

However, some studies suggest that keto may boost fat burning and enhance endurance, making it ideal for low-intensity, steady-state exercises such as jogging, cycling, or yoga.

So, how long should you workout on keto? The answer may depend on your body's ability to adapt to using fat for fuel instead of carbs. Initially, you may experience reduced energy levels and a decrease in performance, but these effects typically improve over time as your body becomes keto-adapted.

To optimize your workouts on keto, focus on low-intensity exercises and consider the timing of your carb intake. You may also need to adjust your macronutrient ratios, ensuring adequate protein and fat intake to support muscle recovery and growth.

In summary, combining keto with exercise is feasible, but it requires understanding your body's energy needs and making adjustments to your diet and workout routine.

High-intensity exercises may be tougher on keto

The ketogenic diet is a popular choice for those looking to lose weight and improve their health. However, when it comes to working out on keto, there are some important things to consider. While exercising and following a keto diet can be compatible, it's essential to understand that your body will respond differently as it adapts to a new way of fuelling itself.

The Impact of Keto on Exercise Performance

When you restrict carbohydrates on keto, you limit your muscle cells' ability to access sugar (glucose), one of the fastest fuel sources for the body. As a result, your muscles' ability to function at high intensities is impaired for any activity that lasts longer than 10 seconds. This is because, after around 10 seconds of maximal effort, muscles start relying on glucose for energy through a process called glycolysis.

Fat and ketones, the primary fuel sources on keto, cannot replace glucose in the glycolytic pathway. Only after about two minutes of exercise will your body start using metabolic pathways that can burn ketones and fat. This means that keto can limit your performance during high-intensity activities such as:

• Weight lifting with heavier weights and higher rep sets
• Sprinting or swimming for longer than 10 seconds
• Playing sports with minimal rest breaks like soccer, rugby, and lacrosse
• High-intensity interval training or circuit training

Managing the Transition

During the initial transition to keto, your body depletes its glycogen stores, and you may experience a gap in energy supply. This can impact sports and activities that require short, intense movements. To manage this, it's crucial to understand your body's timing for transitioning between energy sources, which varies from person to person.

Fueling Your Workouts on Keto

To ensure optimal performance while exercising on keto, it's essential to get the right amount of fat and protein. Carbs provide a muscle-preserving stimulus, and without them, adequate fat and protein intake becomes even more critical to maintain performance and gain muscle mass. Here are some key considerations:

• Prioritize protein intake: Aim for 1.4-2 grams of protein per kilogram or 0.6-0.9 grams per pound of body weight. If you're highly active or trying to lose weight, consider increasing protein intake to 2.2 grams per kilogram of lean body mass (1 gram per pound).
• Adjust your fat intake: Ensure that around 70% of your daily calories come from healthy fat sources. If you're trying to gain weight, increase your fat intake to achieve a calorie surplus of 250-500 calories. If your goal is weight loss, decrease your fat intake to create a calorie deficit of 250-500 calories.
• Manage your carb intake: Generally, keep your carb intake at 35 grams or less per day. If high-intensity exercises are a significant part of your routine, you may need to increase your carb limit or implement a targeted or cyclical ketogenic diet to improve performance.

Keto and High-Intensity Workouts

While keto can be beneficial for endurance exercises and low- to moderate-intensity workouts, it may be challenging for high-intensity exercises. During high-intensity exercise, the body shifts to using glycogen as fuel, regardless of your macronutrient intake. As carbs are the primary source of glycogen, a keto diet may compromise performance in intense workouts.

Therefore, if you're an athlete or exerciser doing intense workouts like CrossFit or HIIT, it's advisable to consider doing keto during your off-season or when performance is less of a priority.

The Bottom Line

Keto may not be the ideal diet for high-intensity activities, but it can still be a powerful tool for weight loss and improving overall health. To make keto and exercise work together, it's crucial to tailor your diet and workout program to accommodate the effects of carbohydrate restriction on physical performance. This may include adjusting your macronutrient intake, following a targeted or cyclical ketogenic diet, and choosing workout routines that align with the energy pathways favoured by keto.

Keto may boost fat burn

The ketogenic diet is a popular eating plan that encourages the consumption of healthy fats and the restriction of carbohydrates. By limiting carbs, the body enters a state of ketosis, where it burns fat as a fuel source instead of carbohydrates. This can lead to weight loss, boosted energy, and improved blood sugar control.

One of the key questions surrounding the keto diet is its impact on exercise performance. While some claim that keto can enhance endurance and fat-burning, others argue that it may drain energy levels and impair high-intensity workouts.

Evidence for Fat-Burning

Several studies have found that the keto diet may boost fat-burning during exercise. One small study involving competitive race walkers showed that the keto diet increased the body's ability to burn fat during training, even at different intensity levels. Another study involving 22 athletes found that switching to a keto diet increased fat-burning over a four-week period.

Additionally, a 2018 study found that when overweight adults replaced carbohydrates with fat in their diet for five months, they burned approximately 250 more calories per day compared to those on a high-carb, low-fat diet. This is because fat contains significantly more calories per gram than carbs or protein.

The Drawbacks

While keto may boost fat-burning, it is important to note that it may not enhance overall athletic performance. The keto diet can impair access to glucose, the primary fuel source for high-intensity exercises. As a result, the keto diet may limit performance during high-intensity workouts that require short bursts of energy, such as weightlifting or spinning.

Furthermore, the keto diet can initially lead to reduced energy levels as the body adapts to using fat for fuel instead of carbohydrates. This transition period can leave individuals feeling less energised during workouts.

Maximising Fat-Burning on Keto

To maximise fat-burning while on the keto diet, it is recommended to focus on low-intensity, steady-state exercises such as jogging, biking, rowing, or yoga. These types of exercises are less affected by the keto diet and can help individuals stay within the fat-burning zone.

Additionally, ensuring adequate protein intake is crucial for muscle maintenance and recovery. Aim for a protein intake of 1.4-2 grams per kilogram or 0.6-0.9 grams per pound of body weight, depending on your activity level and goals.

In conclusion, while the keto diet may boost fat-burning, it is important to consider the potential drawbacks and make adjustments to your exercise routine and diet to optimise results.

You may feel less energised at first

When you start the keto diet, you may experience a period of adjustment where you feel less energised than usual. This is because the keto diet involves severely restricting your intake of carbohydrates, which are your body's main source of energy. As your body gets used to burning fat for energy instead of carbohydrates, you may feel less energised, especially during workouts. This is known as the "keto-flu" and typically passes within a few days.

During this initial period, it is recommended that you stick to your usual workout routine and avoid trying any new, intense workouts. You should also be cautious when doing activities that require quick reactions, such as riding a bike on busy roads.

Some people may also experience mental fog or grogginess during the first few days of the keto diet, as your brain adjusts to using ketone bodies created by breaking down fats in the liver instead of glucose from carbohydrates as its primary fuel source. This can affect your performance during workouts.

To help with the transition, it is important to make sure you are consuming enough calories and not undereating. People on the keto diet are likely to undereat because they are restricting an entire food group (carbohydrates), and the diet also has an appetite-suppressing effect. However, reducing calories too much and combining that with working out will not only make you feel unwell but can also affect your performance and results.

Your body may burn calories quicker

A 2018 study found that when overweight adults replaced carbohydrates in their diet with fat for a period of five months, their bodies were able to burn approximately 250 more calories per day than people who ate high-carbohydrate and low-fat diets. This is because when in ketosis, the body isn't using glycogen as its energy source. Instead, it's using fat and ketone bodies.

However, it's important to remember that gram per gram, fat is more calorie-dense than carbohydrates. Each gram of fat has 9 calories, while a gram of protein or carbohydrate has 4 calories.

This difference in caloric burn can add up when it comes to weight loss. To lose weight, the body needs to burn more calories than it takes in.

The Ketogenic Diet and Exercise

The ketogenic diet is a very low-carb, high-fat, moderate-protein diet that has been linked to a range of potential health benefits, 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 argue that it could drain energy levels and make muscle growth more challenging.

The Bottom Line

There is no one-size-fits-all answer to how long you should work out on keto. The duration and intensity of your workouts will depend on your individual fitness level, goals, and how your body responds to the keto diet.

If you're new to keto, it's important to start slowly and listen to your body. You may experience a decrease in energy levels and athletic performance during the initial transition phase as your body adjusts to using fat for fuel instead of carbohydrates.

Over time, as your body becomes "keto-adapted," you may find that you can work out for longer periods without getting tired, especially with low- to moderate-intensity exercises.

Tips for Exercising on Keto

• Focus on low- to moderate-intensity exercises such as jogging, biking, swimming, and yoga.
• Avoid high-intensity exercises such as sprinting, boxing, or high-intensity interval training, as these rely primarily on carbohydrates for fuel.
• Make sure to eat enough fat on the keto diet. Aim for around 70% of your daily calories from healthy fat sources.
• Prioritize protein intake to maintain and build muscle mass. Aim for 1.4-2 grams of protein per kilogram or 0.6-0.9 grams per pound of body weight.
• Consider a targeted ketogenic diet or cyclical ketogenic diet if you engage in high-intensity workouts regularly. These approaches involve strategically timing your carb intake around your workout times or having dedicated refeeding days.
• Listen to your body and adjust your diet and workout routine as needed.

Keto is better for maintaining muscle mass than adding it

The ketogenic diet is a very low-carb, high-fat, and moderate-protein diet. It is often used for weight loss, but it has also been linked to other health benefits, such as improved blood sugar control and decreased hunger levels. However, its effects on athletic performance, particularly muscle growth, are still a subject of debate. While the keto diet may be suitable for maintaining muscle mass, there are several reasons why it may not be ideal for maximising muscle growth.

Firstly, muscle growth requires adequate protein intake to promote muscle synthesis and tissue repair. On a keto diet, excessive protein consumption can kick the body out of ketosis, as the body can convert protein into glucose. Therefore, keto diets are typically considered moderate-protein diets, with protein making up only 15-20% of total calories. This lower protein intake may not be sufficient to support optimal muscle growth.

Secondly, keto diets are often calorie-deficit diets, as they restrict carbohydrates, the body's main source of energy. Consuming more calories than expended is necessary to maximise muscle growth. The reduced calorie intake on a keto diet, combined with the body's adaptation to using fat as its primary fuel source, can make it challenging to increase muscle mass.

Additionally, carbohydrates are essential for muscle growth as they are stored in the muscle cells as muscle glycogen, providing an immediate fuel source for high-intensity activities. On a keto diet, the body has limited access to carbohydrates, which can impair performance during high-intensity workouts. While keto diets may enhance endurance and fat-burning capabilities, they may not be optimal for activities requiring short bursts of intense energy, such as weightlifting or sprinting.

Furthermore, the transition to a keto diet can be challenging, with initial side effects including decreased energy levels, fatigue, and the "keto flu," which includes symptoms such as nausea, irritability, and insomnia. This adjustment period can impact workout performance and make it more difficult to build muscle.

In summary, while the keto diet may be effective for maintaining muscle mass, it may not be the best approach for maximising muscle growth due to its impact on protein and calorie intake, reduced carbohydrate availability, and potential negative effects on high-intensity exercise performance. For individuals specifically looking to add muscle mass, other dietary approaches may be more suitable.

Frequently asked questions