Should Athletes be on Ketogenic Diet? Here are the Pro's and Con's of Keto Diet
Ketogenic diets have become quite popular in recent years as countless people cut carbs to lose weight and improve their health.
The question is, should athletes be on a keto diet, and if so, should all athletes be on a keto diet. Or are carbs an indispensable part of diets designed to optimize physical performance?
Let’s dive into the science and see where the truth lies.
What Changes Occur In The Body On a Ketogenic Diet?
To understand the impact of keto dieting on athletes, we first have to know what changes occur as we eliminate nearly all carbs from our daily menu.
Ketogenic dieting serves to switch your body from a state of glycolysis (using carbs as its primary energy source) to ketosis, where the body breaks down ketones for energy (1). The state is known as ketosis and occurs within two to four days of reducing your carb intake to 50 or fewer grams. Insulin levels drop as your body produces more and more ketone bodies to fuel internal processes (1).
Ketosis is your body’s response to a lack of carbs. In simple terms, you’re forcing your body to start using fats for fuel.
Keto For Athletes: Does It Help You Perform Optimally?
Keto dieting has grown in popularity among competitive populations, with more athletes adapting low-carb diets to improve their performance and recovery.
One reason why keto dieting benefits athletes is because of the metabolic adaptations that take place.
This study shows entering a state of ketosis makes athletes much better at burning fat for energy, with fat oxidation rates increasing as much as two-fold (2).
Being able to metabolize fat more efficiently is beneficial for endurance athletes simply because of the sheer energy availability through adipose tissue, even in relatively lean athletes (3). In essence, keto allows you to tap into the enormous energy reserves in your body and use them more efficiently during training.
On a high carb diet a long endurance session would drain your limited glycogen stores and you would suffer from a performance drop (4, 5). Unless you could refuel during your exercise session. Being keto-adapted puts you in a position where you no longer rely on your bodies limited carb sources (6).
Just as endurance athletes are adopting the ketogenic lifestyle, we see more high-intensity athletes experiment with the low-carb approach. Examples include soccer and rugby players who rely on quick energy production to be explosive on the field.
No this is where the reserach falls short and it becomes more of a personal testing game. Limited research suggest keto-adapted athletes can perform well in more intense activities. sometimes even surpassing their previous performance on a high-carb diet (7, 8).
However, according to this study there are some reasons to believe that keto adaptations can occur more slowly for high-intensity athletes than for endurance athletes (8).
According to some experts, the time it takes could be two to three times longer. One potential reason is that fat-burning allows for a steady energy supply for muscle cells, leading to good endurance performance. But, more intense activities rely on quicker energy production, which might not occur readily after an athlete starts following a ketogenic diet.
Can Ketosis Speed Up Recovery?
There is some research that suggest ketosis may help prevent inflammation. Which means it could possible help athletes recovery. (9). Again the research is limited but it could be promising.
Many athletes report being able to recover much faster from demanding races and competitions, returning to regular training sooner than their people who follow a high-carb diet.
Another benefit of ketosis is that fat loss occurs more effortlessly, which benefits athletes, particularly those who must maintain a certain weight for competitions (1, 2, 6). Easier fat loss also means athletes don’t have to spend as much time in a calorie deficit and can achieve their body composition goals more quickly (10).
Losing fat but retaining muscle also improves your power-to-weight ratio, making you more efficient and competitive. For example, a runner carrying less weight but having the same amount of muscle as someone heavier would burn fewer calories, suffer from less joint stress, and set better times.
The Unknown of Keto
The keto diet is fairly new and the research is far from conclusive. In this Study it does demonstrate that there was not a performance decrease between a high carb diet and a low carb diet but there is a problem.
They only tested high intensity athletes up to a 25 min workout. They have no idea what happens after the 25 min mark. And they are uncertain if 25 min was enough time to completely deplete the available glycogen stores.
Here’s What We Know at Cell Sauce
For 2 years we tested a low carb diet plan with several of our athletes and here what we discovered. For endurance athletes under 80% VO2 Max and under 85% max heart rate we saw long lasting energy and no performance decline with a low carb diet.
However - with many of our motocross and mountain bike athletes we saw big performance declines.
Here’s what was happening.
For a motocross athlete there training day can consist of three 30 minute motos with approximately 30-45 mins rest between. During a 30 minute moto an athlete would hit 90-95% VO2 Max and 100 Max Heart rate. In this situation we see our athletes exceed the 80% VO2 Max the 85% max HR and the 25 min exercise length.
On the first moto of the day our athletes energy, intensity and output was good. Second moto we saw a decline in intensity and energy. The perceived effort for the same output was also increased.
On the last moto our riders were tired, lethargic and even suffered from a lack of focus. The perceived effort was higher, lap times slower. Overall - we saw a larger performance decline when on a low carb diet vs a high carb diet.
Lastly - during a low carb diet we saw slow recovery times. When our riders finished a training day they ate a recovery meal. The rest of the day our athletes lacked energy, lacked motivation and experienced lethargy. Often times this lack of energy would carry over into the following day. This makes sense considering the time difference to metabolize fat vs the time it takes to metabolize carbohydrates.
What we saw during our test was clear. If your training requires high intensity exercise lasting more than 30 minutes, or if you’re required to do multiple high intensity sessions during a day a low carb diet did not work.
So until further research is available or a better strategy is discovered our high intensity athletes at Cell Sauce utilize carbohydrates to reach peak performance.
The Conclusion is Blurry
Research is far from conclusive on any nutritional approach to optimizing athletic performance and recovery. But here’s our suggestions. If you’re an endurance athlete and your sport keeps your HR under 85% max and your VO2 under 80% max then you should test a keto diet. But be prepared for an adaption period for the first few weeks.
If you’re a high intensity athlete like our motocross and mountain bike athletes you can try a keto diet but I would advise against it. We’ve adopted a train high rest low approach. What that means is, on days were we have really high output we increase our carbohydrate intake, on recovery days or days we are doing base training we have a lower carbohydrate intake.
Every athlete requires different nutrition to perform optimally. Your job is to test, track and be aware of how your body responds to the fuel you give it.
If you want help with nutrition plans, meal plans and fitness programs for cyclists, runners, mountain bikers and motocross riders check out CellSauce.com/Pro
- Masood W, Annamaraju P, Uppaluri KR. Ketogenic Diet. [Updated 2021 Nov 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-.
- Prins, Philip J et al. “High Rates of Fat Oxidation Induced by a Low-Carbohydrate, High-Fat Diet, Do Not Impair 5-km Running Performance in Competitive Recreational Athletes.” Journal of sports science & medicine vol. 18,4 738-750. 19 Nov. 2019
- Thomas DM, Gonzalez MC, Pereira AZ, Redman LM, Heymsfield SB. Time to correctly predict the amount of weight loss with dieting. J Acad Nutr Diet. 2014;114(6):857-861. doi:10.1016/j.jand.2014.02.003
- Hearris MA, Hammond KM, Fell JM, Morton JP. Regulation of Muscle Glycogen Metabolism during Exercise: Implications for Endurance Performance and Training Adaptations. Nutrients. 2018;10(3):298. Published 2018 Mar 2. doi:10.3390/ nu10030298
- Mata F, Valenzuela PL, Gimenez J, et al. Carbohydrate Availability and Physical Performance: Physiological Overview and Practical Recommendations. Nutrients. 2019;11(5):1084. Published 2019 May 16. doi:10.3390/nu11051084
- Ma S, Suzuki K. Keto-Adaptation and Endurance Exercise Capacity, Fatigue Recovery, and Exercise-Induced Muscle and Organ Damage Prevention: A Narrative Review. Sports (Basel). 2019;7(2):40. Published 2019 Feb 13. doi:10.3390/ sports7020040
- Antonio Paoli A, Mancin L, Caprio M, Monti E, Narici MV, Cenci L, Piccini F, Pincella M, Grigoletto D, Marcolin G. Effects of 30 days of ketogenic diet on body composition, muscle strength, muscle area, metabolism, and performance in semi professional soccer players. J Int Soc Sports Nutr. 2021 Sep 16;18(1):62. doi: 10.1186/s12970-021-00459-9. PMID: 34530857; PMCID: PMC8447662.
- Chang CK, Borer K, Lin PJ. Low-Carbohydrate-High-Fat Diet: Can it Help Exercise Performance?. J Hum Kinet. 2017;56:81-92. Published 2017 Mar 12. doi:10.1515/ hukin-2017-0025
- Pinto A, Bonucci A, Maggi E, Corsi M, Businaro R. Anti-Oxidant and Anti Inflammatory Activity of Ketogenic Diet: New Perspectives for Neuroprotection in Alzheimer's Disease. Antioxidants (Basel). 2018;7(5):63. Published 2018 Apr 28. doi: 10.3390/antiox7050063
- Strasser B, Spreitzer A, Haber P. Fat loss depends on energy deficit only, independently of the method for weight loss. Ann Nutr Metab. 2007;51(5):428-32. doi: 10.1159/000111162. Epub 2007 Nov 20. PMID: 18025815.