KETO & CROSSFIT ATHLETES
In recent years, CrossFit has become a staple in the athletic environment and since Paleo, a low carbohydrate diet is often associated with CrossFit, understanding the influence of the ketogenic diet could shed light on how these diets influence high-intensity activity.
STUDY 1 – THREE MONTHS
In one study, recreationally-trained CrossFit athletes were recruited and placed on one of two diets for 12 weeks. Group one was instructed to follow a ketogenic style of eating while group two ate as usual, (a more balanced approach).
Before and after the commencement of the study, participants underwent performance testing by completing a 1-rep max back squat, maximum repetition pushup test, and a 400m run.
After completing baseline testing, the intervention commenced. During this time, blood was analyzed to ensure ketosis to know that athletes were following the diet. During this time, subjects continued participating in standard CrossFit classes.
The results of the study revealed there was little influence on performance when using a ketogenic diet. Notably, however, it was reported that control participants experienced improvements in their back squat one-rep max and VO2 peak while those in the ketogenic diet group did not (10).
Summary: No benefit of using the ketogenic diet with control participants improving performance to a greater extent than keto participants.
STUDY 2 – SIX WEEKS
In the second study of a shorter duration, researchers recruited recreationally trained CrossFit athletes and placed them randomly into either a ketogenic diet group or a control. During this time, subjects in the ketogenic diet group were instructed to eat as much as they desired, but to keep carbohydrate consumption to 50 grams or fewer per day. Blood ketone measurements were administered to ensure that subjects were in ketosis.
Before the commencement of the six-week intervention, participants underwent baseline performance testing with the following:
- 500-meter row
- 40 bodyweight squats
- 30 abdominal sit-ups
- 20 hand-release push-ups
- 10 pull-ups
Upon completion of baseline performance testing, the subjects took part in the six-week intervention where they completed CrossFit workouts of the day, otherwise known as WODs, four times per week, for time. Upon completion of the six-week study, subjects then repeated the baseline performance metrics to understand if the ketogenic diet afforded growth, performance decline, or neither.
Interestingly, the findings were similar to study one in that there was no significant benefit or decrement as a result of using the ketogenic diet. It was noted that the ketogenic diet subjects displayed significantly greater weight and body fat loss than control (11).
However, a closer look at the dietary practices of participants in the ketogenic diet group shows us they were on average, consuming 200-400 fewer calories by weeks four through six, compared to control, which could explain the difference in weight loss, rather than due to the ketogenic diet.
Summary: No performance benefit of the ketogenic diet. Keto participants did, however, eat fewer calories, resulting in more significant body composition changes.
Based on the limited evidence in CrossFit athletes, it appears that the ketogenic diet has little influence on performance during standard CrossFit workouts compared to a regular diet.
However, it’s important to note there weren’t any direct performance benefits afforded by the ketogenic diet, but in one case, use of the diet did result in worse performance than control, which should be considered.
Based on research alone, preference should ultimately be the deciding factor with regards to how you consume food as a CrossFit athlete. However, extrapolating based on the current data suggests that the ketogenic diet might not be the best choice for the CrossFit athlete since there was no significant performance benefit and the ketogenic diet can often be difficult to maintain.
USE OF THE KETOGENIC DIET IN OTHER SPORTS