Many people have been following low-carb diets, such as the keto diet, today.

These diets, which have existed for a long time, share similarities with paleolithic diets.

Studies have found lower-carb diets to promote weight loss and improve various health markers, but the evidence on performance, strength, and muscle growth is mixed.

Many people have a keto diet plan for weight loss. Here we take a look at low-carb diet and exercise performance of ketosis diet.

Low-Carb and Keto Diets Explained

The low-carb diet guidelines vary between authorities and studies.

Research suggests that low-carb diet is classified as consuming not more than 30% of calories from carbs, but an average low-carb diet involves a daily intake of 50–150 grams of carbs, a moderate-to-high fat intake, and a fairly high amount of protein.

However, low carb can still mean over 200-gram carbs daily for some people, especially athletes. It basically varies from person to person.

A well-formulated keto diet, on the other hand, is more restrictive than the low-carb diet. It only involves 30–50 grams of carb intake daily together with a moderate protein intake and a very high fat intake.

This very low carb intake can help you get into full ketosis, which is a process where your body uses ketones and fat as the main fuel source.

Types of a Keto Diet

There are different types of the keto diet, but here we give you only three of them.

Standard ketogenic diet (SKD). This type of keto diet involves extremely high-fat (75%), moderate-protein (20%), and low-carb (5%) diet.

Targeted ketogenic diet. In this diet, you are allowed to add carbs, usually around periods of intense workouts or exercise.

Cyclical ketogenic diet: This type of keto diet involves periods of higher-carb refeeds, such as 2 high-carb days from 5 keto days.

In most low-carb and keto diets, people limit their consumption of carb-rich foods, such as rice, grains, cereals, sweets, potatoes, beans, and some fruits.

But some follow carb cycling as an alternative approach, wherein they regularly include high-carb periods or refeeds in their low-carb or keto diet.

Low-Carb Diets and Fat Adaptation

When you’re on a low-carb diet, like the keto diet, your body goes through a process known as fat adaptation where it becomes more efficient at using fat as the fuel source. The drastic reduction of carb intake increases ketone bodies, which are a byproduct of fat metabolism.

Ketone bodies can provide energy when there is no sufficient carbs, during long exercise periods, during a prolonged fast, or even for individuals with uncontrolled type 1 diabetes.

What’s more, ketones can partly fuel even the brain.

Keto diets are known to have several beneficial properties: they were found to treat cancer, diabetes, neurological diseases, and risks for cardio and respiratory diseases.

The potency of fat adaptation on a keto diet is great. In fact, a study in ultra-endurance athletes demonstrated that keto dieters burned up to 2.3 times more fat in a 3-hour exercise session.

Although low-carb and keto diets are known to have potential health benefits, their effects on exercise performance are still being examined.

Low-Carb Diets and Muscle Glycogen

The body converts dietary carbs into glucose, which is absorbed into the bloodstream and turns into blood sugar.  With the help of insulin, it travels into the cells of the body and provides the main fuel for moderate and high-intensity exercise.

For many years, eating carbs has been repeatedly found to help with exercise performance, especially during endurance exercise.

Unfortunately, the body is only able to store enough carbs (glycogen) for ~2-hour exercise. After the depletion of glycogen, a condition called “hitting the wall” or “bonking” will arise, where a person experiences decreased endurance performance, tiredness, and fatigue.

That is why most endurance athletes carb up the day before a game or follow a high-carb diet or consume carb supplements of food during exercise.

Low-carb diets, since they don't contain enough carbs, cannot help optimize the reserves of stored glycogen in the muscles.

Low-Carb Diets and Endurance Performance

Research has been conducted on utilizing fat as fuel in sports performance.

During workout, a crossover effect occurs wherein carbs provide more energy at higher intensities and fat provides more energy at lower intensities.

Recently, researchers conducted a study on the effect of a low-carb diet on endurance performance. They found that athletes on a keto diet burned mostly fat up to 70% of max intensity as compared to athletes on a high-carb diet who burned only 55%.

However, despite these positive findings, fat may not be able to provide energy fast enough to meet the demands of elite athletes’ muscles.

Thus, further research is necessary to fully elucidate its effects on an athletic population before making any firm recommendations.

Nevertheless, low-carb diets were found to help prevent tiredness during prolonged workouts. They may also improve one’s health without compromising low-to-moderate intensity endurance performance. In addition, they were also found to help you lose fat.

What’s more, low-carb diets can teach your body to burn more fat, which is quite beneficial when it comes to preserving muscle glycogen during workouts.

How Carbs Affect the Growth of the Muscle

To date, no evidence can prove that a low-carb or keto diet is beneficial for strength, power-based, high-intensity sports.

This is due to the fact that carbohydrates aid muscle growth and high-intensity endurance performance in many different ways:

Carbs promote recovery. Carbohydrates actually help with recovery post workout.

Carbs produce insulin. Carbs provide insulin, which helps with the delivery and absorption of nutrients.

Carbs provide fuel. Carbohydrates play a key role in the anaerobic and ATP energy systems, which are the primary sources of fuel for high-intensity sports.

Carbs reduce muscle breakdown. Carbs also help reduce muscle breakdown, which can potentially be beneficial in the net protein balance.

Carbs improve neural drive. During exercise, carbs can help improve neural drive, mental focus, and resistance to fatigue.

It is important to note that a very high-carb diet, like a typical Western diet, is not recommended for sports, but a moderate-carb or carb cycling diet may work well.

In fact, a diet that involves moderate carb and higher protein seems to be beneficial for body composition and muscle growth for lean and active people.

Are Low-Carb Diets Beneficial for Athletes?

One good thing about a low-carb or keto diet is that it teaches the body to burn and use fat as the fuel source.

Low-carb diets are shown to help preserve glycogen stores and keep athletes from “hitting the wall” during intensity sports.

Relying less on carbs during a race is good for athletes who have difficulty digesting and consuming carbs during exercise. It can also be good during ultra-endurance events where there is a limited access to food.

In addition, several studies have found that low-carb and keto diets promote weight loss and improve overall health.

Fat loss can be beneficial for your fat to muscle ratio, which is particularly essential for intensity sports.

In fact, “train low, compete high” has become a popular training technique where people exercise with low glycogen stores because it can improve fat utilization, enzyme activity, and mitochondria function.

Therefore, following a low-carb or keto diet in the short term, like during an off season, may aid long-term health and performance.

Conclusion

A low-carb and ketogenic diets can be beneficial for healthy, active people who are lifting to stay physically fit and healthy.

However, no solid evidence can prove that they improve performance in athletes. That said, further research is still required to fully elucidate its effects on exercise performance.

Most importantly, carb intake should be tailored to every individual.