Kylie is an 18-year-old female weighing 110 lbs. (50 kg), and 5 feet 8 inches in height. She is a competitive track runner and has excelled in both the 400- and 800-meter dash (high-intensity, moderate duration exercise) in high school, earning a full athletic scholarship to University of Southern California (USC).Kylie's new friends at USC recently started the ketogenic diet and suggested she try it as well. Kylie had always wanted to try a new diet and decided this was the perfect opportunity to do so. Kylie's original diet consisted of 60% carbohydrates, 25% protein, and 15% fat; however, her current daily macronutrient percentages changed drastically to 10% carbohydrates, 20% protein, and 70% fat on the ketogenic diet. After two weeks of being on the ketogenic diet, Kylie's energy levels decreased drastically, she lost 8 lbs., and her running performance has significantly declined. Additionally, her menstrual cycles have become irregular, and her blood work shows significantly reduced levels of LH, FSH, estrogen, testosterone, and T4. Her coach is greatly concerned about both her health and performance and asks for your advice on how to return Kylie to the energetic, vibrant, and great runner she used to be.

1.) Discuss which energy system (i.e., anaerobic or aerobic metabolism) this athlete predominantly utilizes for energy during her sport.

2.) Identify all issues the athlete is experiencing and explain why she may be undergoing them. What actions should be taken to mitigate and/or reverse these symptoms?

3.) Is the athlete demonstrating symptoms of RED-S?