CrossFit athletes are some of the most exceptional physical specimens of all time. The ability to lift heavy and then perform 100 burpees may seem counterintuitive, but many CrossFit athletes do this on a regular basis and strive to improve both their strength and performance times. These individuals need to have the endurance capacity of a long-distance runner with strength-like characteristics of a powerlifter. Due to the uniqueness of the sport and the community as a whole, researchers have been interested in studying what makes these competitive athletes so extraordinary.

running-with-scissors

When discussing CrossFit, it is almost inevitable that a conversation about these individuals’ dietary preferences tends to arise. Heck, if they are willing to take their bodies through the wringer and to extreme levels physically, you would think that there would be some acknowledgement of idea dietary needs. One typical style of eating in the CrossFit community is Paleo.  The Paleo-style diet was popularized by Loren Cordain in 2001 and continued to rise with the spreading of education from some of my colleagues like Robb Wolf (1). In general, the CrossFit nutrition philosophy is centered around  eating “meat and vegetables, nuts and seeds, some fruit, little starch, and no sugar” (2).

food-pyramid

CrossFit-style training has been shown to improve body composition and maximal aerobic fitness in healthy subjects. On average, over 10 weeks, body fat levels dropped about 4% in males and 3.5% in females (3). As you can imagine, the physical demand placed on the body during these workouts is extremely high. Training of such intense nature places a considerable demand on high and continuous glycogenolytic energy production (4). It is generally thought that an inadequacy in CHO intake in these individuals may compromise glycogen repletion and ultimately performance. As a result, some researchers actually suggest astronomically high levels of carbohydrate consumption, such as 8-10 grams/kg/ day for heavily-trained anaerobic athletes (5). For someone who is 175 pounds, that would equate to 640-800 grams of carbohydrates per day. While research tends to show that there is no scientific reason why anyone would ever need to consume this many carbohydrates, it’s eye opening to see those types of recommendations.

Fortunately, not everyone follows the status quo, and in fact many challenge it to help resolve unanswered questions. Recently, two incredible labs from Auburn University and James Madison University set out to look at what happens if you do the complete opposite of some of these recommendations, e.g. what happens when instead of having 20 bowls of cereal a day to hit your 800 grams, you instead had just 30-50 grams total per day and consumed a high-fat, ketogenic diet.

A driving thought behind this question was that many CrossFit athletes tend to eat Paleo and may actually enter in to some state of ketosis during their competition season with the nature of their diet combined with the intense nature of the exercise bouts.  So what if we just took them and bumped their fat up a bit and dropped the carbohydrates even further to induce a state of ketosis? Would these athletes be unable to perform? Would they gain fat rapidly from consuming all of that dietary fat?

Rachel Gregory and her team from JMU recently presented on their findings of 6 weeks of a low-carbohydrate ketogenic diet implemented in athletes performing high-intensity power training as is seen in CrossFit (6). In their study, 27 individuals were randomized into either the control (their normal diet) or a low-carbohydrate ketogenic diet (ad libitum with ≤50 grams of CHO per day) and performed CrossFit workouts 4 times per week. After 6 weeks of training they found that:

ketogenic-control

The LCKD group lost an average of 3.5kg (7.7 lbs), about 3% body fat, and nearly 3kg of fat mass as measured by DXA
No significant difference in protein intake between groups!

Now what about performance? It must have plummeted, right? Wrong. When comparing the two conditions, both groups improved their times over the 6 weeks to the same degree on various tasks such as rows, squats, sit ups, pull-ups, etc.

Recently, researchers from Auburn University investigates physiological responses to ketogenic dieting in cross-trained individuals (7).  Since the paper is still in review, I can tease a few of the high-level interesting findings that have been presented at a recent conference. This study was comprehensive, investigating DXA-determined body composition, ultrasound muscle thickness, resting energy expenditure, performance, and various blood health markers.  Over 12 weeks, DXA-determined fat mass decreased nearly 7.5 lbs more than in the control group, with no significant differences in lean body mass or performance between the two groups.

pulls-up-difficulty

Two different labs using a very similar population finding very similar results is a hallmark of science.  For now, these recent discoveries bring new light to the idea that CrossFit and cross-training athletes may be able to simultaneously improve body composition and maintain performance while following a ketogenic diet. More studies need to investigate this further along with other strategies that may have an effect on performance, such as targeted ketogenic diets (TKD) or even exogenous ketone supplementation.

Keto Conclusions

  • Some research suggests that athletes training Crossfit style should consume high amounts of carbohydrates due to the energy demand of their sport.
  • Paleo is a commonly used dietary strategy in the Crossfit world.
  • Altering the paleo diet by reducing carbs and increasing fat could provide benefit to the Crossfit athlete.
  • New research has displayed not only improved body composition but also improved performance in Crossfit athletes following a ketogenic diet.
keto-conclusions-bar

13 comments on “Crossfit and Keto: What if Fran Ran on Fat?

  1. Mando on

    Question… Were the athletes existing Crossfit athletes or were placed into a new Crossfit type exercise regiment along with the change to diet?

    Reply
  2. Natalie Counts on

    Was there a reason the LCKD group ate less calories per day? It seems the caloric deficit could have also impacted the weight loss. I would have expected this to be a constant for both group to help validate the results. Thoughts?

    Reply
    • Ketogenic Com on

      Great question! This study attempted to capture what happens in real life scenarios therefore calories and macronutrients were suggested however, likely due to the appetite suppressive nature of the ketogenic diet, they ate less calories. Additionally, there were not significant differences, even for protein intake.

      Reply
  3. Richard on

    What was the ratio between fat lost and lean mass lost was this measured? I guess it was but it didn’t show in the graph, this will be important in the long run though!

    Reply
    • Ketogenic Com on

      Great thought Richard! That wasn’t presented in the preliminary findings but I’m sure it will be in the full publication once published! Keep in mind there were no differences for lean body mass between conditions and the ketogenic dieting group lost fat mass so the ratio would be in favor of the ketogenic diets.

      Reply
  4. Chuck W on

    Interesting article. The speed of CrossFit workouts demands that most of the energy in the muscles is generated through glycolysis. If these athletes are eating low carb or ketogenic, how are they replenishing glycogen stores between workouts? From gluconeogenesis in the liver?

    And how much recovery is required between workouts for the average person to replenish glycogen on a low carb or ketogenic diet?

    Thanks!

    Reply
    • Ketogenic Com on

      Great question Chuck! Once fully adapted, individuals on a ketogenic diet actually have the same baseline levels of glycogen stores as someone on a traditional Western diet. This was shown in Dr. Volek’s faster study as well as in an animal study by Dr. Roberts at Auburn University. Though it’s not entirely understood, potential mechanisms are the sparing of glycogen as well as gluconeogenesis from various substrates.

      Dr Volek’s

      Dr. Robert’s

      Reply
  5. Mike G on

    Great article thanks! Maybe I missed it but were they on a Standard keto diet or Targeted or Cyclical?
    I’m a crossfitter and have been researching keto. Some websites say targeted would be better. Thoughts or research to point me in the right direction? Thanks!

    Reply
  6. chett on

    Would be interesting to see if training on a keto diet would increase performance when carbohydrates get re introduced. Ex. training keto but competition = keto and carb- being able to draw from both fuel sources whereas other athletes need carb fuel. I really see this as being the only potential benefit of crossfit style training on a keto diet in serious athletes. The workout they used is simply too short and too easy to give a true indication.

    Reply
    • Ketogenic Com on

      We definitely still need to look more in depth into this to determine if and when they could be reintroduced to improve performance!

      Reply

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