8 Proven Benefits of Intermittent Fasting for Athletes

Intermittent fasting has gained significant attention in recent years for its potential benefits in various aspects of health and fitness. Athletes, in particular, gain numerous advantages from incorporating intermittent fasting into their routines.

This article will discuss the scientific data behind the eight benefits athletes get with intermittent fasting, from strength increase to increased focus.

Intermittent fasting is an eating pattern that alternates between periods of eating and fasting. It doesn’t prescribe specific foods but focuses on when to eat. There are different types of intermittent fasting:

  1. 16/8 Method (Time-Restricted Eating): Also known as the Leangains protocol, this method involves a daily fasting period of 16 hours, followed by an 8-hour eating window.
  2. 5:2 Diet (The Fast Diet): Involves a regular diet five days a week and significantly reduces calorie intake (around 500-600 calories) on two non-consecutive days.
  3. Eat-Stop-Eat: This method involves 24-hour fasts once or twice a week, with a full break from food between dinner on one day and dinner on the next.
  4. Alternate-Day Fasting: Alternating between days of regular eating and days of very low-calorie intake or complete fasting.
  5. Warrior Diet: Involves eating small amounts of raw fruits and vegetables during the day and having one large meal at night within a 4-hour eating window.

Benefits of Intermittent Fasting for Athletes

  1. Increased Strength
  2. Increased Muscular Endurance
  3. Deeper Autophagy
  4. Enhanced Ketosis
  5. Better Weight Management
  6. Improved Metabolic Parameters
  7. Improved Body Composition
  8. Mental Clarity and Focus

1. Increased Strength

Intermittent fasting can positively impact strength through several mechanisms. Fasting periods stimulate growth hormone release,1 a key player in muscle development. Additionally, fasting may enhance the body’s sensitivity to insulin, promoting efficient nutrient utilization by muscles.

According to a study on a 5:2 diet with 12-week resistance training,2 subjects experienced improvements in thigh muscle size and quality and reduced intramuscular and subcutaneous fat.

It’s important to note that these results were achieved by considering moderate protein intake.

2. Enhanced Muscular Endurance

Athletes often seek to enhance muscular endurance to sustain peak performance during prolonged activities, and intermittent fasting helps with this. Fasting triggers the production of mitochondria, the energy powerhouses within cells, leading to more efficient energy utilization.

While human studies are limited, animal studies on alternate-day fasting3 show more efficient energy metabolism and improved running endurance. This may be due to the body’s ability to switch to using ketones4 rather than carbohydrates.

3. Deeper Autophagy

The ability5 of intermittent fasting to induce autophagy has been well-established. For athletes, an increased autophagy means a more effective removal of damaged cells and cellular components.

This process is crucial for maintaining cellular health and preventing the accumulation of dysfunctional elements that impede overall athletic performance and recovery.

However, it’s also crucial to understand that proper nutrition is vital, as lacking it encourages abnormal autophagy,6 which could be more detrimental than beneficial.

4. Enhanced Ketosis

Although not restricting food intake, intermittent fasting facilitates the transition into a state of ketosis,7 where the body primarily relies on stored fat for energy. This is particularly advantageous for endurance athletes, as it prolongs the duration of sustained energy.

The shift to ketosis helps spare glycogen stores, allowing athletes to maintain energy levels during extended periods of physical exertion.

5. Better Weight Management

Athletes are encouraged to manage their weight effectively8 to optimize performance. Intermittent fasting aids in weight management by regulating calorie intake and metabolism.

The restricted eating window naturally limits the opportunity for excessive calorie consumption, promoting fat loss while preserving lean muscle mass. This can be instrumental for athletes aiming to achieve and maintain their ideal body weight.

6. Improved Metabolic Parameters

Intermittent fasting positively impacts various metabolic parameters, including insulin sensitivity and blood sugar regulation.9

Improved insulin sensitivity enhances the body’s ability to utilize glucose efficiently, preventing energy crashes and supporting stable blood sugar levels. This metabolic optimization benefits athletes seeking to optimize their energy metabolism and overall health.

7. Improved Body Composition

Athletes often strive for an optimal body composition10 to maximize their power-to-weight ratio. Intermittent fasting improves body composition by promoting fat loss while preserving lean muscle mass.

This dual effect is valuable for athletes participating in weight-dependent sports or disciplines requiring a lean physique, like distance runners, cyclists, and triathletes.

8. Mental Clarity and Focus

In addition to its physical benefits, intermittent fasting positively influences cognitive function. Improved mental clarity and focus are outcomes of the ketone bodies produced during fasting, which serve as an alternative energy source for the brain.

Athletes can benefit from enhanced concentration and decision-making abilities, particularly during high-stakes competitions or intensive training sessions.

Best Intermittent Fasting Hacks for Athletes

Getting into intermittent fasting could be challenging, but here are some of our favorite hacks to make it easier.

intermittent fasting for athletes

Exercise During the Fasting Period

Strategic timing of workouts during the fasting window can amplify the benefits of intermittent fasting. Exercising in a fasted state encourages the body to tap into stored fat for energy, promoting fat loss and optimizing metabolic adaptations.

Do Not Restrict Calories

One common misconception about intermittent fasting is that it necessitates significant calorie restriction. However, athletes must meet their energy needs to support training demands and recovery.

Maintain Well-balanced Meals

When breaking the fast, athletes should prioritize well-balanced meals that include a mix of macronutrients—protein, carbohydrates, and healthy fats. This helps replenish glycogen stores, provides essential nutrients for muscle repair, and sustains energy levels.

Stay Hydrated

Athletes should prioritize staying well-hydrated throughout the fasting window and pay attention to electrolyte balance. Incorporating water-rich foods and electrolyte-rich beverages can contribute to maintaining optimal hydration levels.

Set Proper Goals

To derive the most benefit from intermittent fasting, athletes should establish clear and realistic goals. Whether the focus is on weight management, improved endurance, or enhanced metabolic health, setting specific and measurable objectives helps guide the fasting protocol.


Intermittent fasting offers a range of scientifically supported benefits for athletes. From increased strength and endurance to improved metabolic parameters and mental clarity, incorporating intermittent fasting into an athlete’s routine can optimize performance and overall well-being.

Frequently Asked Questions (FAQ)

Is intermittent fasting good for athletes?

Yes, intermittent fasting can benefit athletes by promoting muscle development, endurance, and overall metabolic health. Distance runners, cyclists, and triathletes benefit from intermittent fasting more.

What are the disadvantages of intermittent fasting for athletes?

While intermittent fasting has numerous benefits, it may not be suitable for all athletes, especially those with specific medical conditions or intense training schedules requiring constant energy.

What is the 5:2 fasting for athletes?

The 5:2 fasting method involves eating regularly for five days and reducing calorie intake to a quarter of normal for two non-consecutive days. Athletes should carefully plan such regimens to ensure they meet their nutritional needs.

Is intermittent fasting good for fitness?

Yes, intermittent fasting is scientifically beneficial for fitness as it aids in weight management, improves metabolic parameters, and enhances endurance, contributing to overall fitness goals.


1Ho, K. Y., Veldhuis, J. D., Johnson, M. L., Furlanetto, R., Evans, W. S., Alberti, K. G., & Thorner, M. O. (1988). Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. Journal of Clinical Investigation, 81(4), 968-975. https://doi.org/10.1172/JCI113450

2Keenan, S. J., Cooke, M. B., Hassan, E. B., Chen, W. S., Sullivan, J., Wu, S. X., El-Ansary, D., Imani, M., & Belski, R. (2022). Intermittent fasting and continuous energy restriction result in similar changes in body composition and muscle strength when combined with a 12 week resistance training program. European journal of nutrition, 61(4), 2183–2199. https://doi.org/10.1007/s00394-022-02804-3

3Intermittent dietary restriction may boost physical endurance. (2018). Retrieved from https://www.nih.gov/news-events/nih-research-matters/intermittent-dietary-restriction-may-boost-physical-endurance

4Vasim, I., Majeed, C. N., & DeBoer, M. D. (2022). Intermittent Fasting and Metabolic Health. Nutrients, 14(3). https://doi.org/10.3390/nu14030631

5Shabkhizan, R., Haiaty, S., Moslehian, M. S., Bazmani, A., Sadeghsoltani, F., Bagheri, H. S., Rahbarghazi, R., & Sakhinia, E. (2023). The Beneficial and Adverse Effects of Autophagic Response to Caloric Restriction and Fasting. Advances in Nutrition, 14(5), 1211-1225. https://doi.org/10.1016/j.advnut.2023.07.006

6Ichimiya, T., Yamakawa, T., Hirano, T., Yokoyama, Y., Hayashi, Y., Hirayama, D., Wagatsuma, K., Itoi, T., & Nakase, H. (2020). Autophagy and Autophagy-Related Diseases: A Review. International Journal of Molecular Sciences, 21(23). https://doi.org/10.3390/ijms21238974

7Peeke, P. M., Greenway, F. L., Billes, S. K., Zhang, D., & Fujioka, K. (2021). Effect of time restricted eating on body weight and fasting glucose in participants with obesity: Results of a randomized, controlled, virtual clinical trial. Nutrition & Diabetes, 11. https://doi.org/10.1038/s41387-021-00149-0

8Turocy, P. S., DePalma, B. F., Horswill, C. A., Laquale, K. M., Martin, T. J., Perry, A. C., Somova, M. J., & Utter, A. C. (2011). National Athletic Trainers’ Association Position Statement: Safe Weight Loss and Maintenance Practices in Sport and Exercise. Journal of Athletic Training, 46(3), 322-336. https://doi.org/10.4085/1062-6050-46.3.322

9Albosta, M., & Bakke, J. (2021). Intermittent fasting: is there a role in the treatment of diabetes? A review of the literature and guide for primary care physicians. Clinical diabetes and endocrinology, 7(1), 3. https://doi.org/10.1186/s40842-020-00116-1

10Manore MM. Weight Management for Athletes and Active Individuals: A Brief Review. Sports Med. 2015 Nov;45 Suppl 1(Suppl 1):S83-92. doi: 10.1007/s40279-015-0401-0. PMID: 26553496; PMCID: PMC4672016.

Mag. Stephan Lederer, MSc.

Mag. Stephan Lederer, MSc. is an author and blogger from Austria who writes in-depth content about health and nutrition. His book series on Interval Fasting landed #1 on the bestseller list in the German Amazon marketplace in 15 categories.

Stephan is a true man of science, having earned multiple diplomas and master's degrees in various fields. He has made it his mission to bridge the gap between conventional wisdom and scientific knowledge. He precisely reviews the content and sources of this blog for currency and accuracy.

Click on the links above to visit his author and about me pages.

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