Relative Energy Deficiency in sports
The American College of Sports Medicine issued its first position paper on the Female Athlete Triad in 1997. The Triad was described as a syndrome of serious medical conditions that could occur in females who exercise. It was characterized by three inter-related components: disordered or dysfunctional eating, hormonal imbalances such as amenorrhea (the loss of menstrual periods) and osteoporosis.
In reality, several body systems in addition to the reproductive and musculoskeletal systems are affected by low energy (caloric) availability. Another key point is that males are at risk as well as females.
Relative Energy Deficiency Syndrome
A relative energy or caloric deficiency comes about when an individual consumes too few calories to support the full range of body functions involved in optimal health and performance. Energy availability is calculated as dietary energy intake (calories consumed from food) minus the energy cost of purposeful exercise (calories expended during training). Energy availability, in other words, is the amount of dietary energy remaining for other body functions outside of exercise.
Low energy availability can be induced by a reduction in calories (less energy coming in), burning more calories in training than are consumed, or a combination of the two. When energy availability is too low, physiological functions in the body are impaired to reduce the amount of energy being expended, disrupting an array of hormonal and metabolic factors. This includes not only menstrual function and bone health, but also metabolic rate, the immune and cardiovascular systems, protein synthesis, and mental health.
Sometimes athletes end up in an “energy drain” as the result of intense training schedules and inadvertently consuming insufficient calories. More often, however, disordered eating underpins most cases of low energy availability. Male and female athletes who slip into a pattern of restrictive eating or dieting to deliberately lose weight (or body fat) quickly in an attempt to improve their appearance or athletic performance are at risk.
One way the body attempts to conserve energy in response to a continued inadequate intake of calories is to shut down the reproductive system. In females, menses become irregular as the ovaries produce less and less estrogen, and may even stop altogether. Amenorrhea is the diagnosis when three or more consecutive menstrual periods are missed or when menstruation fails to begin in a young woman before the age of 15. Once considered a “normal” part of training or the hallmark of peak fitness, amenorrhea is now viewed as a serious sign that something is amiss in the complex female reproductive system.
With low levels of estrogen that mimic those seen during menopause, the loss of normal bone density accelerates, thereby setting the stage for stress fractures and osteopenia (reduced bone mass), as well as the early onset of osteoporosis. Amenorrheic women between the ages of 16 to 30 lose as much as 2 to 5 percent of their bone mass each year, which is particularly troublesome since peak bone mass is reached during this same interval — age 19 in women and age 20.5 in men.
Cases of RED-S are reported less often in male athletes; however, this may be due simply to under-detection. Metabolic and reproductive hormones also are impaired in a male athlete with low energy availability. For example, below-normal levels of testosterone will be produced, resulting in delayed growth and the slowing of normal body changes (increased muscle mass, for example) associated with puberty or weight training.
Health, performance consequences
RED-S has short- and long-term consequences on an athlete’s health. Immediate consequences of low energy availability include: decreased muscle glycogen stores, fatigue, dehydration, loss of concentration and motivation, depression, electrolyte imbalances, moods swings, poor sleep, increased risk of infections and illnesses (especially colds and other upper respiratory illnesses), and sub-par workouts and performances.
Depending on the degree and duration of the energy deficiency, active teens can suffer from delayed puberty and short stature, nutrient deficiencies such as iron-deficiency anemia, loss of lean muscle mass, lingering overuse injuries, more frequent stress fractures and long-term compromised bone health, as well as an increased risk of developing a full-blown eating disorder.
Athletes at risk
Low energy availability appears to occur among the same at-risk sports for male and female athletes alike. These are the weight sensitive sports in which leanness and body weight are important due to their role in performance (cross-country running, cycling), appearance (gymnastics, cheerleading) or requirement to meet a competition weight category (wrestling, rowing, martial arts).
Competitive athletes often feel intense pressure from coaches, teammates, judges and parents, as well as the media, to meet unrealistic weight goals to improve their performance or visual appeal.
Potential red flags or warning signs for those working with physically active teens and young adults include:
- Dysfunctional or disordered eating (e.g., “too busy” or “forgetting” to eat meals, chronic or extreme dieting, avoidance of all dietary fat, avoiding social eating situations)
- An unbalanced vegetarian eating style (e.g., dislikes dried beans and soy foods or resists eating nutritious foods such as eggs, dairy foods, and nuts, due to their fat content)
- Compulsive or non-purposeful exercise (e.g., excessive exercise beyond a sensible training program, exercising despite an injury, inability to rest or take time off)
- Worrisome weight control practices (e.g., laxative use, self-induced vomiting, use of appetite suppressants)
- Highly self critical, demonstrates low self-esteem and a negative body image
- Poor coping skills to deal with emotional or psychological stress
- Exercise-induced amenorrhea
- Recurrent stress fractures
Prevention is key
The physical “stress” of exercise is not the cause of the disruption of hormones and other metabolic factors associated with RED-S. The problem is low energy availability.
Consuming more calories, a decrease in exercise or a combination of the two, is required to restore an athlete to a state of energy balance. Oftentimes, a gain of 2 to 3 percent of body weight (e.g., approximately 3 to 5 pounds for a 130-pound female) is adequate to restore energy balance and restart the menstrual cycle. Dietary changes alone, however, rarely are enough.
Supplementing with 1,500 milligrams of calcium daily simply keeps an amenorrheic athlete in calcium balance — the added calcium does not build bone, as it can’t compensate for a low estrogen level. Other lifestyle factors such as exercise habits (number of rest days and the volume and intensity of exercise) and methods to manage or cope with stress also must be addressed.
Due to the long-term impact on bone health, any physically active female should seek a thorough medical evaluation if menses become irregular or stop. Body image and disordered-eating issues are often at the root of an athlete’s reluctance to fuel him or herself properly; hence a multidisciplinary treatment approach (medical doctor, registered dietitian and therapist) is recommended.
Suzanne Girard Eberle is a board-certified sports dietitian and the author of Endurance Sports Nutrition (third edition, 2014). Find her at www.eatdrinkwin.com.