A Comparison of the Effects of High-Carbohydrate, High-Protein, and Ketogenic Dietary Regimens on Athletic Performance and Body Composition in Elite Athletes: A Randomized Crossover Trial

Objective: This study aimed to compare the effects of three distinct dietary regimens—high-carbohydrate, high-protein, and ketogenic diets—on athletic performance metrics, body composition, and metabolic parameters in elite athletes.
Methods: A randomized crossover trial was conducted with thirty male athletes over a 12-week period. Participants sequentially followed each of the three dietary interventions. Comprehensive assessments included body composition analysis via bioelectrical impedance, maximal oxygen consumption (VO₂max) measured by respiratory gas analysis, anaerobic capacity evaluated via the Wingate test, and monitoring of biochemical and psychological parameters.
Results: The high-protein diet induced the most significant reduction in body fat mass. Conversely, the high-carbohydrate regimen yielded superior results in the VO₂max test, indicating enhanced aerobic performance. The ketogenic diet, despite promoting weight loss, led to a marked decrease in high-intensity exercise performance and an increase in creatine kinase levels, suggesting greater muscular stress. Furthermore, this diet negatively affected the athletes' mood states.
Conclusion: The findings suggest that optimal dietary choice for athletes must be individualized, based on specific training objectives and personal physiological responses. High-carbohydrate diets appear most beneficial for endurance sports, while high-protein diets are more effective for improving body composition and recovery. The application of a ketogenic diet requires careful consideration and a potentially extended adaptation period due to its mixed impacts on performance and well-being.