Is OMAD Good for Runners? The Pros, Cons, and Risks

November 3, 2025 •

4 min read

Recent studies suggest that while intermittent fasting can offer some health benefits, the extreme restriction of OMAD poses significant challenges for athletes. The question is: is OMAD good for runners, or does the potential for caloric and nutrient deficits outweigh the perceived benefits of a one-meal-a-day regimen?

Quick Summary

This article examines the viability of adopting a one-meal-a-day (OMAD) diet for runners, breaking down the metabolic effects, performance impacts, nutritional hurdles, and potential risks like muscle loss and hormonal disruption. It covers hydration strategies, ideal timing for exercise, and provides a comparative analysis to other dietary patterns for athletes.

Key Points

Performance Impact: OMAD leads to depleted glycogen stores, hindering high-intensity performance and increasing fatigue for runners.
Risk of Muscle Loss: Prolonged fasting can cause the body to break down muscle protein for energy, particularly if dietary protein is inadequate during the single meal.
Poor Recovery: The extended fasting period makes it difficult to time post-workout nutrition effectively, impairing muscle repair and glycogen replenishment.
Nutrient Deficiencies: It is extremely challenging to consume a full day's worth of essential macro and micronutrients in a single, one-hour meal.
Hydration Challenge: Maintaining adequate hydration and electrolyte balance is difficult during a 23-hour fast, potentially leading to cramping and performance decline.
Better Alternatives: Less restrictive eating patterns, such as the 16:8 intermittent fasting or a standard, balanced diet, are generally safer and more sustainable for runners.
Individual Considerations: OMAD is not suitable for everyone and requires professional guidance, especially for athletes or individuals with health conditions.

Understanding the OMAD Approach for Runners

The One Meal a Day (OMAD) diet is an extreme form of intermittent fasting, requiring a 23-hour daily fast followed by a single one-hour eating window. While often pursued for rapid weight loss due to built-in calorie restriction, its compatibility with a runner's high-demand training is a complex issue. For a runner, consistent energy is crucial, but OMAD mandates a long fast that can deplete the body's primary fuel source, glycogen. This raises serious questions about its effectiveness and safety for athletic performance and recovery.

The Metabolic Challenge for Athletes

When a runner embarks on an extended 23-hour fast, the body undergoes a metabolic shift. Initially, it depletes blood glucose and stored glycogen in the liver and muscles. After this, it begins to burn fat for fuel through fat oxidation. For low-intensity, easy-paced runs, a fasted state might be tolerable, but it's a different story for high-intensity training or long-distance endurance. The physiological demands of a hard workout require readily available glucose, which is precisely what the fasting period aims to exhaust. This can lead to a significant drop in performance, fatigue, and impaired cognitive function during training.

Potential Benefits and Significant Drawbacks

Some advocates suggest that OMAD can offer benefits like simplified meal planning and improved insulin sensitivity. However, for the active runner, these potential upsides are often overshadowed by serious drawbacks. A primary concern is low energy availability and muscle loss, as the body may break down protein for energy during prolonged fasts, especially if protein intake during the single meal is insufficient. Furthermore, the restrictive nature can trigger hormonal disruptions and heighten stress hormones like cortisol, potentially hindering recovery and promoting fat storage after a post-run feeding.

The All-Important Recovery and Refueling

Recovery is a cornerstone of any runner's regimen, and nutrition is its foundation. After a run, especially a hard one, the body needs carbohydrates to replenish glycogen stores and protein to repair muscle tissue. The traditional recommendation is to refuel within a 30 to 90-minute window post-exercise. For OMAD runners, this timing can be a major issue, as their eating window may not align with their post-workout needs. Missing this critical refueling period can impair recovery and hinder progress.

The Role of Hydration

Hydration is another critical factor complicated by OMAD. Proper hydration is a continuous, daily process, not just something to consider during the eating window. An athlete's fluid and electrolyte needs are elevated due to sweating. While plain water and black coffee are permitted during the fast, it is challenging to consume enough fluids and replenish electrolytes lost during a long day of fasting, potentially leading to dehydration, cramping, and decreased performance.

Comparison of OMAD with other runner diets


Feature	OMAD Diet (One Meal a Day)	Traditional Runner's Diet (3-5 meals)	16:8 Intermittent Fasting (Time-Restricted Eating)
Energy Availability	Low and inconsistent; prone to crashes and glycogen depletion.	High and consistent; steady energy supply for training and recovery.	Moderate; still allows for consistent fueling around training sessions.
Nutrient Intake	Risk of deficiencies; hard to pack all macros and micros into one sitting.	Easily balanced and managed across multiple meals.	Easier than OMAD, but still requires planning to meet needs in the window.
Muscle Maintenance	High risk of muscle loss, especially with insufficient protein.	Promotes muscle maintenance and growth with consistent protein intake.	Less risk than OMAD, especially if timed correctly around workouts.
Recovery	Impaired; difficult to time post-workout nutrition effectively.	Optimal; easy to consume carbs and protein within recovery window.	Can be managed, but requires planning to not miss the recovery window.
Hydration	Challenging; risk of dehydration due to prolonged fast.	Normal, manageable with consistent fluid intake throughout the day.	Consistent; easier to stay hydrated than on OMAD.

Conclusion: Is OMAD right for you?

While the prospect of weight loss and simplified eating may be appealing, OMAD is generally not recommended for runners due to the high risks to performance, recovery, and overall health. The extreme caloric restriction and extended fasting periods make it exceptionally difficult to fuel high-intensity training, replenish glycogen stores, and repair muscle tissue adequately. For most runners, a more balanced and sustainable approach to nutrition is more beneficial. If weight management is the goal, other forms of intermittent fasting, such as the less restrictive 16:8 method, or simply maintaining a slight and consistent calorie deficit through a balanced diet, are safer alternatives. Always consult a healthcare professional or a registered sports dietitian before making major dietary changes, especially when fueling a demanding running regimen. Your long-term health and running performance should always take precedence over short-term trends.

This content is for informational purposes only and is not medical advice. For professional guidance, consult a healthcare provider or a registered dietitian.

Frequently Asked Questions

Yes, OMAD can lead to rapid weight loss due to significant calorie restriction, but it often comes at the cost of muscle mass and athletic performance. Safer and more sustainable methods, like a moderate calorie deficit spread across several meals, are generally recommended for runners.

The best time to run on OMAD is either right before your single meal or a couple of hours after it. This allows you to either refuel immediately after exercise or use recently consumed energy for your workout, mitigating some of the performance risks associated with a fully fasted state.

OMAD can lead to muscle loss because the body, starved of its preferred fuel sources (glucose and glycogen) during a prolonged fast, may start breaking down protein from muscle tissue for energy. It is also difficult to consume enough protein in one sitting to support muscle repair and growth.

A runner’s OMAD meal should be extremely nutrient-dense to compensate for the long fasting period. It needs to include high-quality lean protein, complex carbohydrates, healthy fats, and plenty of vegetables and fruits to cover all macro and micronutrient needs.

Yes, less restrictive intermittent fasting methods, such as the 16:8 protocol, are generally better for runners. A 16-hour fast allows for a longer eating window, making it easier to meet nutritional needs and time fueling around training sessions.

Yes, OMAD can negatively affect running performance by depleting glycogen stores and reducing energy availability, which can lead to fatigue, decreased endurance, and an impaired ability to perform high-intensity efforts.

Yes, maintaining hydration is a significant challenge on OMAD. With no fluid or electrolytes consumed during the long 23-hour fast, runners face an increased risk of dehydration and electrolyte imbalances, which can cause cramping and reduced performance.