Is Running While Fasting Good

Is running while fasting a good idea? As an avid runner, I have often wondered about the benefits and drawbacks of running on an empty stomach. Fasting has become a popular practice for weight loss and other health benefits, but does it positively or negatively impact our running performance? Let’s dig deeper into this topic and explore the science behind it.

The Science Behind Fasting

Fasting is the act of abstaining from food or drink for a specific period. There are various forms of fasting, ranging from intermittent fasting, where you restrict your eating window each day, to longer-duration fasts lasting over 24 hours.

The idea behind fasting is that it allows our bodies to tap into stored energy, such as glycogen and body fat, for fuel. It is believed to promote fat loss, improve insulin sensitivity, and even provide anti-aging benefits. However, when it comes to running, fueling our bodies properly is crucial for optimal performance.

The Impact on Running Performance

Running while fasting can affect our performance in several ways. Without consuming food or carbohydrates before a run, our glycogen stores may be depleted, leading to reduced energy levels and potential fatigue. This can make it challenging to maintain a high level of intensity and endurance during exercise.

Additionally, running on an empty stomach may impair our ability to utilize carbohydrates efficiently. Carbohydrates are the primary fuel source for moderate to high-intensity exercise, and without an adequate supply, our bodies may rely more on protein for energy. This can lead to muscle breakdown and hinder our overall performance.

Potential Benefits

While there are potential drawbacks to running while fasting, some individuals may find benefits from this practice. One possible advantage is increased fat burning. When our glycogen stores are depleted, our bodies are more likely to use stored fat as a fuel source. This can be beneficial for those looking to lose weight or improve body composition.

Another potential benefit is the mental challenge fasting while running can provide. It requires discipline and mental toughness to push through a workout without the usual energy from food. Some runners may find this aspect of fasting beneficial for building mental resilience and pushing their boundaries.

Considerations and Recommendations

While running while fasting may have its potential benefits, it is essential to consider individual factors and exercise caution. Here are a few recommendations to keep in mind:

  1. Listen to your body: Pay attention to how you feel during and after a fasted run. If you experience excessive fatigue, dizziness, or other discomfort, it may be a sign that you need to fuel before your runs.
  2. Stay hydrated: Fasting can increase the risk of dehydration, so make sure to drink enough water before and after your runs.
  3. Gradually build up: If you are new to running while fasting, start with shorter and less intense runs to give your body time to adapt.
  4. Consider the timing: If you do choose to run while fasting, consider scheduling your runs for shorter durations or lower intensities to minimize the impact on performance.


In conclusion, running while fasting can have both potential benefits and drawbacks. While it may promote fat burning and mental resilience, it can also lead to decreased energy levels and impaired performance. Ultimately, the decision to run while fasting should be based on individual preferences, goals, and listening to your body.

As an avid runner, I believe it’s essential to prioritize proper nutrition and fueling for optimal performance. While fasting can offer certain advantages, it’s crucial to find a balance that allows us to perform at our best while considering our bodies’ needs.