Low-carb and ketogenic diets are becoming increasingly popular among those who want to lose weight or improve their health. However, these diets not only impact body weight but also affect energy levels, physical performance, and mental state. In this article, we will review the potential effects of these diets, including the initial difficulties and the adaptation process.
Initial challenges: the “keto flu”
When someone starts a ketogenic or low-carb diet, the body needs time to adapt. During the first few days or weeks, many people may experience symptoms known as the “keto flu,” which include fatigue, headaches, irritability, concentration difficulties, and low energy levels. This occurs because the body is transitioning from using glucose as its primary energy source to using ketones, which are derived from fat breakdown.
The keto flu is usually temporary and typically subsides within a few days or weeks as the body adjusts to the new fuel source. During this period, it is important to stay properly hydrated and replenish electrolytes (sodium, potassium, magnesium) since a decrease in these can exacerbate symptoms.
The effect of low-carb diets on energy levels
The impact of low-carb diets on energy levels can be mixed and largely depends on how well an individual adapts to the diet. After overcoming the initial difficulties, many people experience more stable energy levels throughout the day, as fluctuations in blood sugar levels are minimized. Ketones, as an energy source, provide sustained energy for many people without the sudden drops in energy that are common with carb-rich diets.
On the other hand, some people feel they cannot obtain enough energy from a low-carb diet, especially during high-intensity workouts. This is particularly true if the body has not yet fully adapted to burning fat. In such cases, performance may temporarily decrease, especially during high-intensity, short-duration activities where carbohydrates serve as a quick energy source.
Physical performance and sports
The effect of low-carb diets on physical performance is also a double-edged sword. Endurance athletes, such as marathon runners or cyclists, often benefit from a ketogenic diet because their bodies become more efficient at burning fat during workouts, providing long-term energy.
However, in sports that require quick bursts of power and strength, such as sprinting, weightlifting, or team sports, where rapid energy supply is crucial, low-carb intake can be disadvantageous. Glycogen, stored energy derived from carbohydrates, is vital for high-intensity exercises, and its lack can reduce performance.
For those engaged in such sports, a “cyclical ketogenic diet” or a “targeted ketogenic diet” may provide a solution. These diets involve timing carbohydrate intake around specific periods, such as pre-workout, to maximize performance without leaving ketosis.
Mental state and concentration
The effects of low-carb diets on mental state can also vary. Many people report improved concentration, better memory, and more stable moods after transitioning into ketosis. Research suggests that ketones provide an efficient energy source for the brain and may contribute to enhanced cognitive functions.
On the other hand, during the transition period, or if the diet is not properly balanced, cognitive decline, concentration difficulties, and mood swings may occur. This is especially true for those who do not maintain proper electrolyte balance or consume enough fat in their diet.
Long-term effects
In the long term, if the diet is well-structured, low-carb diets can provide sustainable energy and stable performance. However, it is important that the diet includes all necessary nutrients and is tailored to individual needs. For some people, a moderate reintroduction of carbohydrates may be necessary to achieve optimal performance, especially if they lead an active lifestyle.
