The Effects of a Six-Week Ketogenic Diet on CrossFit Performance Parameters: A Pilot Study

Abstract

Background: CrossFit is a popular high-intensity functional training method. Despite the importance of muscle glycogen in fueling such high-intensity efforts, research exploring the use of a ketogenic diet in CrossFit practitioners is limited. Objectives: To conduct an experimental trial examining the effects of a 6-week ketogenic diet on CrossFit performance parameters. Methods: Eight men and seven women (N = 15; 30.2 ± 4.11 years) were recruited for this experimental study design and were randomly assigned to either the ketogenic diet (KD; n = 8) or the control group (CON; n = 7) for 6 weeks. Several measures of anaerobic performance were assessed at baseline and after 6 weeks utilizing the following series of standardized exercise tests: timed 500 m row, Wingate Anaerobic Test, and 3-repetition maximum (3-RM) deadlift. Aerobic capacity was also assessed by measuring VO2peak. In addition, body composition was assessed via BodPod. Results: Multiple 2 X 2 mixed factorial analyses of variance were performed for measures of body composition and aerobic and anaerobic performance variables. No significant differences in body composition (p < 0.05), anaerobic performance (p < 0.05), or aerobic performance (p < 0.05) were observed between groups. Conclusion: A 6-week ad libitum KD had no effect on exercise performance or body composition in CrossFit practitioners. Our findings demonstrate that a KD does not impair CrossFit performance, which may be of interest to those considering a KD when participating in CrossFit.