Athletes on Keto: Boosting Performance with Low Carbs

The ketogenic diet, known predominantly for its weight-loss prowess and health benefits, is taking the athletic world by storm. While carbohydrates have historically been the mainstay of an athlete’s diet, many are now turning to fats as their primary fuel source. But can athletes truly thrive on a low-carb diet? Let’s delve into the fascinating world of keto for athletic performance.

Why Athletes Are Considering Keto

The basic premise of the ketogenic diet is to shift the body’s primary energy source from carbohydrates to fats. This leads to the production of ketones, which the body uses for energy in the absence of glucose. The proposed benefits for athletes include:

  1. Consistent Energy: By relying on fat – an abundant energy source even in lean athletes – energy levels can be more consistent without the highs and lows of carbohydrate burning1.
  2. Enhanced Fat Oxidation: Training on keto can enhance the body’s ability to burn fat, potentially preserving glycogen stores for critical moments in exercise2.
  3. Reduced Recovery Time: Early research suggests a ketogenic diet may reduce inflammation, potentially aiding recovery post-exercise3.

Adaptation: The Key to Success

One of the key factors in successfully merging athletics with keto is the adaptation period. Athletes transitioning to a ketogenic diet often experience a temporary decline in performance. This is a crucial phase where the body becomes ‘fat-adapted’, shifting its primary energy metabolism from carbs to fats4.

Once the body is keto-adapted, which can take several weeks, many athletes report a return to their previous performance levels and, in some cases, experience performance enhancement, especially in endurance sports5.

Types of Athletes Who Might Benefit

While keto shows promise for various athletic endeavors, it seems particularly suited to:

  1. Endurance Athletes: Those involved in marathons, triathlons, or long-distance cycling often benefit from the sustained energy release from fat oxidation6.
  2. Strength Athletes: Some bodybuilders and powerlifters use keto during their cutting phase, aiming to shed body fat while retaining muscle7.
  3. Recreational Athletes: The health benefits of keto, combined with adequate energy for exercise, make it a viable option for fitness enthusiasts.

However, athletes involved in short-duration, high-intensity sports may need to incorporate targeted carbohydrate intake around their training sessions8.

Practical Tips for Athletes on Keto

  1. Stay Hydrated: Ketosis can lead to increased fluid loss. Athletes should prioritize hydration and replenish electrolytes9.
  2. Prioritize Protein: While keto is moderate in protein, athletes might need slightly more to support muscle repair and growth.
  3. Consider Carb Cycling: Introducing carbs around intense training sessions or on high-volume days can provide added fuel10.
  4. Monitor Performance: Use training logs to track how the diet impacts performance, and be ready to make necessary adjustments.
  5. Seek Expert Guidance: A sports nutritionist can provide personalized advice, optimizing the diet for individual needs.

Potential Pitfalls

  1. Initial Performance Dip: As mentioned, there’s often a decline in performance during the adaptation phase.
  2. Micronutrient Deficiency: Athletes need to ensure they’re getting essential vitamins and minerals, as limiting carbs can reduce intake of certain nutrients11.
  3. Energy Imbalance: Athletes burn significant calories. They must ensure adequate caloric intake to support their training and recovery.


The ketogenic diet’s place in the athletic world is still a topic of research and debate. However, anecdotal evidence and emerging studies hint at its potential benefits, especially for endurance sports. Like any dietary strategy, keto’s success for athletes depends on individualized planning, monitoring, and adaptation. Always consult with professionals to ensure optimal health and performance.


  1. Phinney, S. D. (2004). Ketogenic diets and physical performance. Nutrition & Metabolism, 1(1), 2.
  2. Volek, J. S., Noakes, T., & Phinney, S. D. (2015). Rethinking fat as a fuel for endurance exercise. European journal of sport science, 15(1), 13-20.
  3. Youm, Y. H., Nguyen, K. Y., Grant, R. W., Goldberg, E. L., Bodogai, M., Kim, D., … & Kang, S. (2015). The ketone metabolite β-hydroxybutyrate blocks NLRP3 inflammasome–mediated inflammatory disease. Nature medicine, 21(3), 263-269.
  4. Burke, L. M. (2015). Re-Examining High-Fat Diets for Sports Performance: Did We Call the ‘Nail in the Coffin’Too Soon?. Sports Medicine, 45(1), 33-49.
  5. Webster, C. C., Noakes, T. D., Chacko, S. K., Swart, J., Kohn, T. A., & Smith, J. A. H. (2016). Gluconeogenesis during endurance exercise in cyclists habituated to a long‐term low carbohydrate high‐fat diet. The Journal of physiology, 594(15), 4389-4405.
  6. Volek, J. S., Freidenreich, D. J., Saenz, C., Kunces, L. J., Creighton, B. C., Bartley, J. M., … & Lee, E. C. (2016). Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, 65(3), 100-110.
  7. Paoli, A., Grimaldi, K., D’Agostino, D., Cenci, L., Moro, T., Bianco, A., & Palma, A. (2012). Ketogenic diet does not affect strength performance in elite artistic gymnasts. Journal of the International Society of Sports Nutrition, 9(1), 34.
  8. O’Neal, E. K., Poulos, S. P., & Bishop, P. A. (2011). Hydration profile and influence of beverage contents on fluid ingestion by women during outdoor recreational walking. Journal of strength and conditioning research, 25(6), 1647-1655.
  9. Maughan, R. J., & Griffin, J. (2003). Caffeine ingestion and fluid balance: a review. Journal of human nutrition and dietetics, 16(6), 411-420.
  10. McSwiney, F. T., Wardrop, B., Hyde, P. N., Lafountain, R. A., Volek, J. S., & Doyle, L. (2018). Keto-adaptation enhances exercise performance and body composition responses to training in endurance athletes. Metabolism, 81, 25-34.
  11. Paoli, A., Rubini, A., Volek, J. S., & Grimaldi, K. A. (2013). Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European journal of clinical nutrition, 67(8), 789-796.

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