Adhering to a ketogenic diet is a popular nutritional strategy, but the lack of carbohydrate energy is bound to change the typical cardio day. A study published in the Journal of the International Society of Sports Nutrition suggests men are better able to utilize dietary fat for energy compared to females.
Eleven CrossFit trained males and females followed a ketogenic diet for 4 weeks. After returning to their normal diet, these subjects participated in an incremental cycling test. Males experienced an increase in fat utilization at around 65% of exercise capacity and this increase became even more noticeable when exercise intensity approached 80% of capacity. This shift in macronutrient utilization was not as prevalent in female subjects.