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Does Citrulline Break a Fast?

Pure L-citrulline does not break a fast when taken in its isolated form. This amino acid supplement contains no calories and does not trigger an insulin response, allowing individuals to maintain their fasted state while potentially benefiting from its effects on athletic performance and blood flow.

Intermittent fasting has become a popular dietary approach for those seeking to improve their health and manage their weight. As more people adopt this eating pattern, questions arise about which supplements can be consumed during fasting periods without disrupting the fast. L-citrulline, an amino acid often used by athletes and fitness enthusiasts, is one such supplement that has garnered attention.

The Science Behind L-Citrulline and Fasting

L-citrulline is a non-essential amino acid that plays a crucial role in the body’s urea cycle. This cycle helps detoxify ammonia and convert it into urea for excretion. Naturally found in foods like watermelon, L-citrulline is also synthesized in the body from other amino acids. Many individuals take L-citrulline supplements to enhance athletic performance, improve blood flow, and reduce muscle fatigue.

When considering whether L-citrulline breaks a fast, it’s essential to understand the concept of fasting itself. Fasting typically involves abstaining from caloric intake for a specific period. The primary goal is to maintain a state of metabolic fasting, where the body relies on stored energy sources like glycogen and fat rather than incoming calories. The main concern for those who fast is whether consuming certain supplements or foods will trigger an insulin response or provide enough calories to shift the body out of the fasted state.

Impact on Insulin and Blood Sugar Levels

Research supports the notion that L-citrulline does not significantly impact insulin levels or glucose metabolism. According to a study published in the Journal of Strength and Conditioning Research, L-citrulline supplementation did not alter plasma glucose or insulin levels in healthy individuals. This finding suggests that taking L-citrulline during a fasting period is unlikely to disrupt the metabolic state associated with fasting.

Furthermore, another study indicated that L-citrulline supplementation improved blood flow and reduced blood pressure without affecting insulin sensitivity. These results provide additional support for the use of L-citrulline during fasting periods, as it appears to offer potential benefits without interfering with the fasting state.

Caloric Content and Additives

One of the primary concerns with any supplement during fasting is whether it contains calories or triggers an insulin response. Pure L-citrulline does not break a fast because it is calorie-free and does not elicit an insulin response. Still it is crucial to ensure that the L-citrulline supplement is pure and free from additives such as sugars or non-caloric sweeteners, which could potentially affect insulin levels.

When choosing an L-citrulline supplement for use during fasting periods, it’s essential to read the label carefully. Some products may contain additional ingredients that could potentially break a fast. For example, certain L-citrulline supplements include additives like beetroot powder or sucralose, which might impact insulin response and thus break a fast.

Choosing the Right L-Citrulline Supplement

For those who practice intermittent fasting and wish to integrate L-citrulline into their regimen, selecting a pure form of the supplement is advisable. Look for products that contain only L-citrulline without any additional ingredients or fillers. Some recommended options include fermented L-citrulline powders and pure L-citrulline supplements that do not contain any additives that could potentially break a fast.

When purchasing L-citrulline supplements, always check the ingredient list to ensure that the product contains only L-citrulline. Avoid supplements that include added sugars, artificial sweeteners, or other ingredients that might affect blood sugar levels or trigger an insulin response.

Dosage and Timing Considerations

The recommended dosage for L-citrulline to enhance athletic performance typically ranges from 6,000 to 8,000 mg per day. For optimal results, it is best taken 30-40 minutes before a workout to maximize its benefits, such as increased blood flow and nutrient delivery to muscles. If taken during fasting hours, it should be consumed with water or other non-caloric beverages to avoid breaking the fast.

When incorporating L-citrulline into a fasting regimen, it’s vital to consider the timing of supplementation. Some individuals may prefer to take L-citrulline during their eating window to ensure it does not interfere with their fast. Others may choose to take it during fasting periods, especially if they exercise while fasted. Ultimately, the decision depends on individual goals and preferences.

Potential Benefits of L-Citrulline During Fasting

While L-citrulline does not break a fast, it may offer several benefits when taken during fasting periods. Some potential advantages include:

  1. Improved blood flow: L-citrulline may enhance nitric oxide production, leading to better circulation and oxygen delivery to muscles.
  2. Reduced muscle fatigue: By promoting better blood flow, L-citrulline may help reduce muscle fatigue during exercise.
  3. Enhanced exercise performance: Some studies suggest that L-citrulline supplementation may improve endurance and power output during physical activity.
  4. Cardiovascular support: L-citrulline may help lower blood pressure and improve overall cardiovascular health.

It’s vital to note that while these potential benefits exist, individual responses to L-citrulline supplementation may vary. As with any supplement, it’s advisable to consult with a healthcare professional before adding L-citrulline to your fasting regimen.

Key Takeaways

  1. Pure L-citrulline does not break a fast when taken in its isolated form.
  2. L-citrulline does not contain calories or trigger an insulin response.
  3. Choose pure L-citrulline supplements without additives to maintain a fasted state.
  4. L-citrulline may offer potential benefits for exercise performance and cardiovascular health.
  5. Consult a healthcare professional before adding L-citrulline to your fasting routine.


In conclusion, L-citrulline appears to be a safe supplement to consume during fasting periods, provided it is taken in its pure form without additives. Its lack of caloric content and minimal impact on insulin levels make it compatible with most fasting protocols.

Still as with any dietary change or supplement regimen, it’s essential to listen to your body and consult with a healthcare professional if you have any concerns.

L-citrulline may offer potential benefits for those who fast, particularly in terms of exercise performance and cardiovascular health, but individual responses may vary.

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