Keto diet

Short answer: The keto diet turns the body into a fat-burning machine by restricting carbohydrates to 20-50 grams daily and using ketone bodies for energy, which is particularly beneficial for endurance sports. Practical advice: For athletes relying on high-intensity activities, it's crucial to carefully plan protein intake (1.6-2.2 g/kg body weight) to maintain muscle mass without exiting ketosis.

Keto diet is a nutritional regimen that minimizes carbohydrate intake, using fat as the primary energy source.

Related reading: The complete guide to sports nutrition — a fundamental guide from the expert team at Sport Zona.

What is the keto diet?

The ketogenic, or keto diet, is a nutritional regimen that radically alters the body's metabolism by significantly restricting carbohydrates in favor of fats. Typically, carbohydrates are limited to 20-50 grams per day, protein is moderate (around 1.2-1.7 grams per kilogram of body weight), and the rest of the calories come from fat. This macronutrient composition forces the body to switch from using glucose as its primary energy source to fats and ketone bodies.

This approach is not new; it has a long history in medical contexts, particularly in treating refractory epilepsy. In recent years, however, the keto diet has gained popularity among the general public, including athletes, due to its potential benefits for weight management, improving metabolic health, and supporting energy levels.

How does the keto diet work?

When carbohydrate intake is drastically limited, glycogen stores in the liver and muscles become depleted. The body, seeking an alternative fuel source, begins to break down fats into fatty acids. Some of these fatty acids are transported to the liver, where they are converted into ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone). This metabolic process is called ketogenesis, and the state where the body actively produces and uses ketone bodies for energy is called ketosis.

Ketone bodies can cross the blood-brain barrier and serve as an efficient energy source for the brain, which normally relies on glucose. Additionally, most body cells can also utilize ketone bodies. This shift towards "fat burning" as the primary energy source is the basis of the keto diet's effects. Low insulin levels, induced by low carbohydrate intake, also help break down and prevent fat accumulation.

Key stages of the change:

• Depletion of glycogen stores.
• Increased fat breakdown.
• Production of ketone bodies in the liver.
• Utilization of ketone bodies for fuel by the brain and muscles.

Why is the keto diet important for athletes?

The keto diet is a nutritional system that offers athletes several potential advantages by providing a stable and nearly unlimited energy source from fat, which is particularly beneficial for endurance sports where glycogen stores are quickly depleted.

However, the National Strength and Conditioning Association (NSCA) recommends a carbohydrate intake of at least 3-5 g/kg of body weight for athletes engaged in moderate to high levels of activity. On the keto diet, this intake is drastically lower, which can compromise high-intensity activities relying on anaerobic metabolism, such as sprinting or weightlifting. For strength sports, adequate protein intake (1.6-2.2 g/kg body weight) is critical for maintaining muscle mass, which is possible on a keto diet but may require careful planning to avoid exceeding the moderate level and exiting ketosis. The keto diet can support weight management and body composition by reducing appetite and improving blood sugar control, which is important for weight-class sports.

What are related concepts to the keto diet?

• Ketosis — A metabolic state that is the goal and primary mechanism of the keto diet, where the body uses ketone bodies for energy.
• Carnivore Diet — An extreme form of the ketogenic diet that focuses on animal products, eliminating plant-based foods.
• Gluconeogenesis — The process of synthesizing glucose from non-carbohydrate sources in the liver, important for maintaining blood sugar levels on a keto diet.
• Anabolism — The process of building complex molecules from simpler ones, which can be challenging to maintain on some forms of the keto diet due to limited insulin and carbohydrate availability.