Understanding Relative Energy Deficiency in Sport (RED-S) and the Female Athlete Triad

It’s uplifting seeing your athlete dedicate themself to a sport they love. But too many hours in the gym or practice can lead to problems if they are not fueling their body appropriately. “Athletes underestimate how many calories they should be consuming,” says Logan Caplan, MD, a primary care sports medicine physician at Children’s.

When young athletes overtrain and undereat, they may lack the energy their bodies need for athletic performance, as well as for healthy development and daily life. Relative Energy Deficiency in Sport (RED-S) is a condition of impaired physiologic functioning caused by low energy availability and includes, but is not limited to, impairments of metabolic rate, menstrual function, bone health, immunity and cardiovascular health.

What Is the female athlete triad?

Part of RED-S is the condition known as the female athlete triad, which includes low energy availability, poor bone health and irregular or missed periods, which can co-exist with disordered eating.

What is low energy availability?

When energy output (from exercise and daily life) exceeds energy input (from food), this is considered low energy availability or a relative energy deficiency. This can be caused by not getting enough calories, overdoing it with physical training or both. When this happens, athletes exhaust their stored energy during athletic activities, which leaves less energy available for daily life.

It can be tricky to find the right balance when it comes to calorie consumption. Young athletes may not realize just how much fuel their body needs to function during high-intensity training and competition. Sometimes it’s purely a lack of awareness that leads athletes to eat too little. However, sometimes decreased intake may be intentional. Either way, it is important to identify this caloric insufficiency as soon as possible.

How to help your athlete get the fuel they need

If you and your child are uncertain what types of foods and how many calories are appropriate for their level of activity, talk to your pediatrician or a primary care sports medicine provider. They can refer you to a dietitian who can help design a meal plan that provides your athlete with enough fuel to keep their energy levels up, which can help avoid the complications associated with RED-S. Athletes who may not have disordered eating but follow a strict diet like vegetarianism or veganism may also be at risk for inadequate caloric intake, so they should speak with a dietician or their doctor about strategies to meet their nutritional needs.

Signs your athlete is struggling with disordered eating

It’s important to keep in mind that not eating enough can also be a sign of disordered eating (extreme and inconsistent eating patterns). When dieting, skipping meals and rigid routines around food become associated with guilt, shame or anxiety, that is a sign that your child may have disordered eating. “Generally, disordered eating is the practice of unsafe or unhealthy habits in order to lose weight or to promote ‘healthfulness.’ More serious eating disorders like bulimia nervosa and anorexia nervosa are psychiatric diagnoses that can be life threatening,” says Dr. Caplan.

Some signs that your child may have an unhealthy relationship with food include:

• Preoccupation with body image (whether appropriate for their sport or not)
• Fluctuating weight
• Following diet trends
• Using diet pills or supplements (including laxatives or diuretics)
• Under or overeating, or vomiting after meals
• Using exercise, fasting or food restriction to “make up for” consuming food

While, disordered eating and eating disorders are more common amongst females, they are certainly not limited to female athletes. Anyone, male or female, can struggle with these unhealthy eating habits. Some sports are at particularly increased risk of disordered eating:

• Sports emphasizing appearance (dance, gymnastics, figure skating, diving)
• Weight-class sports (wrestling, boxing, rowing)
• Sports in which lower weight may be an advantage (running, high jump, pole vault, cycling)

If you notice any of the signs above in your child, talk to your pediatrician. A consultation with a mental health specialist may be recommended.

One key sign of low energy availability in female athletes is menstrual dysfunction. This includes irregular menstrual cycles—missing periods during the sports season and getting them back in the off-season. Or it may mean a complete lack of menstruation.

What is amenorrhea?

The absence of menstrual periods is called amenorrhea. “Amenorrhea can be due to a variety of reasons, such as endocrine, structural or other disorders. Low energy availability in the female athlete triad or RED-S is just one cause,” says Dr. Caplan.

However, menstrual dysfunction is common in female athletes, particularly in sports that require high endurance or high energy output like running and gymnastics. Parents should be concerned and talk to their child’s pediatrician if their daughter:

• Has not had her first period by age 15.
• Misses three periods in a row or has more than three months without a period.
• Often has periods that are irregular/unpredictable or are spaced more than five weeks apart.
• Reports they “lose their period” during the season.

Why is amenorrhea a concern?

Amenorrhea or menstrual irregularity that is left untreated may represent an underlying estrogen deficiency. Low estrogen can have lasting effects on your daughter’s health, including delayed puberty and loss of bone density.

Talk to your daughter about the importance of a regular menstrual cycle. Encourage her to keep track of her periods and to notify you or her doctor of any changes.

Bone mineral density, or the amount of minerals like calcium in the bones, is a key indicator of bone health. Typically, we reach optimum bone density around age 18, so bones are still growing and changing in younger athletes.

When an athlete has low energy availability, hormone levels shift and negatively affect bone mineral density. Low bone mineral density is known as osteopenia. It’s measured on a spectrum. At its lowest, decreased bone mineral density can lead to osteoporosis.

“Osteoporosis in a child or adolescent is defined by a low bone mineral density, and/or a significant fracture history. This is a severe outcome of the female athlete triad and RED-S,” says Dr. Caplan.

How to improve bone mineral density

If your child experiences multiple stress fractures or a single high-risk stress fracture as determined by their doctor, it’s important to have him or her evaluated for low bone mineral density. Identifying this condition early can help limit bone loss and future problems. Your child’s doctor may recommend the following to help restore bone mass:

• Sufficient caloric intake to ensure proper energy availability
• Resuming healthy menstruation, which may require a period of inactivity
• Incorporating weight-bearing exercises into training if lacking
• Supplementing with calcium and vitamin D

“It’s important to take steps to prevent further bone loss and slowly recover bone mineral density,” says Dr. Caplan.

The signs of RED-S and the female athlete triad can range from subtle to more severe. If you have any suspicion that your child may be experiencing effects of low energy availability, a Children’s sports medicine physician can help.

Our team is specially trained to care for youth and teen athletes, so they can identify problems that might go unnoticed by a doctor who only treats adults, provide care tailored to growing bodies, and offer insight to help get kids back to the activities they love.