The ketogenic diet (keto for short) is a diet that relies on very few carbohydrates, moderate proteins and lots of healthy fats. It was originally developed to treat epilepsy, but is now enjoying great popularity, especially in the areas of weight loss, performance optimization, muscle building, and general health. Many bodybuilding pro athletes use keto as part of their bodybuilder fitness plan to optimize fat loss while preserving muscle mass.

In this article, you will learn what the ketogenic diet is, how it works, what benefits it offers and how you can integrate it into your daily routine.

1. What is the Ketogenic Diet?

The ketogenic diet is based on a drastic reduction in carbohydrates, which causes the body to switch from using glucose (sugar) as its primary energy source to burning fat. This change leads to the formation of ketone bodies, which are produced in the liver from fat and serve as an alternative energy source.

Macronutrient Distribution (Guideline Values):

• Fat : 70–80%
• Protein : 15–25%
• Carbohydrates : 5-10% (20-50g per day)

Many IFBB and NPC athletes combine keto with targeted supplements to maintain muscle performance.

2. How Does the Ketogenic Diet Work?

Normally, the body gets its energy from carbohydrates, which are converted into glucose. However, when carbohydrates are scarce, blood sugar levels drop and the body begins to use fat reserves.

This state is called Ketosis. In Ketosis:

• The body uses ketone bodies from fat as its main energy source.
• Insulin levels are lowered, which promotes fat burning.
• Blood sugar levels remain stable, which prevents energy crashes.

Especially in strength training and bodybuilding, a well-thought-out ketogenic diet can help reduce body fat while maintaining muscle.

The ketogenic diet focuses on minimal carbohydrates, but there are also strategies that strategically adjust carb intake to optimize muscle growth and fat loss. Learn more about the effects and benefits of carb cycling in this article: Carb Cycling – Effective Nutrition Strategy for Muscle Growth & Fat Loss.

3. Benefits of the Ketogenic Diet

a) Weight Loss

• The body burns more fat, both from food and from the body's own reserves.
• The reduced insulin secretion prevents fat storage.

b) Improved Mental Clarity and Energy

• Ketone bodies are an efficient source of energy for the brain, which can lead to better concentration.
• The consistent energy supply prevents “sugar crashes”.

c) Stabilization of Blood Sugar Levels

• Ideal for people with insulin resistance or type 2 diabetes.
• Reduces food cravings.

d) Supporting Health

• Reduction of inflammatory markers.
• Potential protection against neurodegenerative diseases (e.g. Alzheimer's).
• Improved cholesterol and triglyceride levels.

Disadvantages of the Ketogenic Diet

Despite its benefits, the ketogenic diet also comes with some disadvantages, especially for strength athletes and bodybuilders. Since carbohydrates are the primary source of energy for intense exercise, there may be a loss of performance during high-intensity exercise such as heavy weight training sessions or HIIT. Cutting out carbohydrates reduces glycogen stores in the muscles, which can lead to lower exercise performance.

In addition, the diet is difficult for many people to maintain in the long term because it entails social restrictions and a limited choice of food.

Another disadvantage is the potential for muscle loss if protein intake is too low or if the body breaks down muscle tissue to generate energy during a strict ketosis phase. Health-wise, caution is also advised: long-term high fat consumption, especially unsaturated fats, can increase the risk of cardiovascular disease if the quality of the fats is not taken into account.

4. Foods in the Ketogenic Diet

Allowed foods:

• Fats : Avocados, olive oil, butter, coconut oil, nuts and seeds.
• Proteins : meat, fish, eggs, poultry.
• Vegetables : Green leafy vegetables, zucchini, cauliflower, broccoli, peppers.
• Dairy products : cheese, cream, Greek yogurt (unsweetened).
• Other : nut butter, dark chocolate (min. 85%), keto snacks.

Foods to avoid:

• Sugary foods (sweets, soft drinks).
• Starchy foods (bread, pasta).