Thus, there is the need to evaluate the efficacy of the KD, not only with respect to energy metabolism, but also with respect to discipline-specific performance capacity. For food intake recording, the participants used food diaries and electronic kitchen scales. The dieticians gave instructions to each participant individually on how to use the scales and complete the diaries. Participants recorded the time and amount of foods and beverages consumed at each meal, the amount of leftovers, and any deviations from the diet. Based on the above facts, we hypothesized that in actively training male and female CrossFit practitioners, a KD for 4 weeks would induce shifts in fuel utilization during exercise in favor of fat utilization.