How Emma Navarro’s RED-S diagnosis gave her life back, and what it means for athletes
Emma Navarro’s rise into tennis’ upper echelon was as swift as it was steady. The American, born in New York and raised in Charleston, climbed from world No. 149 at the start of 2023 to No. 8 just 20 months later by taking an arduous route. She played more singles matches than nearly all of her peers for two years straight. She seized every opportunity to compete with gusto, even if it meant…
In 2023, American tennis player Emma Navarro, born in New York and raised in Charleston, quickly rose through the ranks. She climbed from world No. 149 to No. 8 within just 20 months. To reach this height, Navarro played more singles matches than most of her peers for two consecutive years. Even if it meant competing in lower-ranked WTA 125 events, she never shied away from the challenge.
Her breakout year on tour was in 2024, where she defeated second-ranked player Aryna Sabalenka at the BNP Paribas Open, ousted Coco Gauff from Wimbledon and the U.S. Open, and secured a singles spot on the U.S. Olympic team for the Paris Games. However, in 2026, Navarro's journey took a different turn. She began the year with a packed schedule, securing four wins before mid-March.
But after losing her opening round match at a WTA 125 tournament in Austin to world No. 100 Lulu Sun, she took two months off the tour. In a series of emotional Instagram posts, Navarro announced her decision to end her 2026 season and focus on her health. She revealed that she had been diagnosed with Relative Energy Deficiency in Sport (RED-S), a condition where the body doesn't receive enough energy from food to support both exercise demands and daily functions.
This condition, which is more commonly diagnosed in women, is often misinterpreted and under-discussed. Navarro's experience, however, challenges this assumption and contributes to a broader conversation about athlete health. Along with her RED-S diagnosis, Navarro mentioned being diagnosed with Hashimoto's hypothyroidism, a condition where the thyroid gland doesn't produce enough hormones, leading to symptoms like fatigue, weight gain, joint pain, and mental health issues.
In her social media posts, Navarro detailed symptoms that had been affecting her since 2023, including moodiness, extreme hunger, a weakened immune system, and difficulty remembering and articulating thoughts. She emphasized that her feelings were unlike anything she had experienced before and that she felt "off" to a severe degree.
The RED-S diagnosis came in the fall of 2025, according to Dr. Anna Roby, a registered dietitian and physiologist specializing in the condition. Dr. Roby clarified that RED-S can affect athletes of any gender, sport, or body type. She emphasized that if an individual can move their body, they are at risk of developing RED-S. As a result, experts, including Dr. Emily Kraus, director of Stanford’s Female Athlete Science and Translational Research program, commend Navarro for sharing her experience.
They stress the importance of raising awareness and advocating for healthy training and fueling habits in all sports, not just endurance sports. Diagnosing RED-S is challenging due to its exclusion-based nature, as symptoms can be attributed to various other medical issues. Additionally, symptoms can be nonspecific, such as fatigue or persistent injuries, which might seem like part of normal life for athletes who travel extensively for competitions.
While Kraus and Roby were not directly speaking about Navarro’s case, they highlighted that athletes often assume experiencing REDs symptoms to be a normal part of high performance. Diagnosing RED-S requires understanding and acceptance by the athlete, recognizing the abnormality of their symptoms, and seeking appropriate medical help.
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