A runner misses her period for one month. Then three. Then six. While she brushes this abnormality off as being normal or even convenient, it shouldn’t be taken lightly. Absent menstrual cycles are a key symptom of Relative Energy Deficiency in Sport, or RED-S, a largely invisible condition that poses dangerous health consequences. Increasing awareness of RED-s, creating healthy training environments and promoting proper nutrition is critical for ensuring long-term well-being.
RED-S arises when overtraining and underfueling makes an athlete’s dietary intake insufficient for their energy expenditure. It’s estimated that RED-S impacts 15% to 80% of athletes and is primarily seen in women.
“This season in football, we had a student who felt extremely tired all the time, but didn’t know why,” football coach and PE teacher Joseph Luo said. “It turned out to be low energy availability, as his body started to shut down from not having enough calories. He had to get enough rest, rehydrate and take proper care to recover.”
The long-term consequences of RED-S stretch far beyond poor performance. Inadequate nutrition and — in the case of female athletes — a lack of periods lead to low bone density, increasing the risk of fractures and osteoporosis. This is especially devastating for student athletes, who are in a critical period for bone development. RED-S can also cause fatigue and depression, impair hormonal glands and weaken the immune system.
“When athletes don’t replenish properly, the body uses up all the glycogen, causing exhaustion, and begins slowing down its metabolism,” said Toni Gist, clinical assistant professor of food science and nutrition at University of Illinois Urbana-Champaign. “After prolonged restriction, it’s vital to see a clinical registered dietician.”
Certain sports carry higher risks of developing RED-S. Artistry-based sports like figure skating or gymnastics often create unrealistic body standards by tying lean physiques with athletic success. Similarly, sports with weight classifications, such as wrestling, subject athletes to weigh-ins that can incentivize rapid weight loss. Endurance athletes experience a higher risk of underfueling due to their intense training.
“During my junior year games, I’d be so tired due to underfueling, as it was a stressful year and I had less time to eat before and after games,” senior and water polo captain Michael Lee said. “It hurt my performance and when I got injured or sore, it was hard for me to recover.”
Athletic culture plays a major role in RED-S development. Youth sports have become increasingly competitive, with athletes training harder and restricting food intake under the pressure to succeed. Team environments can also reinforce this harmful cycle through body-shaming and pressuring athletes to work beyond their limits.
“I used to put pressure on myself to gain weight, but now people encourage me to do my best,” senior and water polo player Andrew Wu said. “In my team, we’re supportive in helping each other out because we know nutrition matters.”
Social media only adds fire to the fuel, exposing youth to a flood of fitness and diet content — from physique transformations to “what I eat in a day” videos — promoting unhealthy comparison.
“I definitely have seen a lot of stuff promoting being skinnier and not eating enough,” senior Xiaoya Gao said. “It’s a social standard that paints a toxic image of what we should be and affects our relationship with food.”
To prevent RED-S, it’s important for sports culture to shift the focus from athlete weight to nutrition and proper fueling. Student athletes need extra calories, as well as ample rest and hydration, to support their energy expenditure and long-term health.
“I always tell my athletes to make sure they’re eating enough calories, hydrating and getting ample sleep,” Luo said. “In my classes, I go over things like micronutrients, macronutrients, how they’re processed in the body and calorie tracking.”
Athlete health can be supported through expanding nutritional education, allowing students to be more informed on their bodies and needs. Furthermore, normalizing nonjudgmental conversations around nutrition can help athletes recognize warning signs before they escalate.
