Relative Energy Deficiency in Sport (RED-S) builds upon the Female Athlete Triad (Triad). The Triad has been understood as the syndrome relating energy deficiency, or low-energy availability (LEA), with menstrual disturbances and low bone-mineral density in exercising women and female athletes. Having any one of the three components of the Triad is sufficient for diagnosis, and the first recommended treatment is nutritional therapy (increasing calories). Very recently, a similar male athlete triad was introduced—made up of LEA, reduced sex-hormone production, and low bone-mineral density. RED-S applies to both males and females, expands the three components of the Triad, and suggests that other body systems (such as digestion) and athletic performance are similarly compromised by LEA. While more research is needed to fully understand the additional components of the new RED-S model, it’s clear that LEA can be a root cause of many health and performance concerns in active men and women.
Low-energy availability
The calories you eat in your diet fuel every function in your body, including your ability to exercise. However, when the energy you expend exceeds what you take in, your body can adapt in unhealthy ways. Energy availability is calculated by subtracting the number of calories you burn specifically through exercise from the total number of calories you eat during the day. Low-energy availability means that your body doesn’t have access to enough calories to perform its normal day-to-day functions in addition to the energy requirements for exercise. This can be due to a person not eating and drinking enough calories during the day, exercising in high volumes, or both.
Resting metabolic rate (RMR), or the number of calories you burn at rest, accounts for the majority of the energy you spend throughout the day. This varies based on your sex, age, body composition, and other factors. You also burn calories moving throughout the day. This includes any physical movement you do—like performing daily household chores or walking around your office—in addition to exercise. Finally, you experience the thermic effect of food by burning energy while eating and drinking, digesting what you consumed, and absorbing those nutrients. To maintain your weight, you need to take in enough calories to make up for that total energy expenditure.
The available energy after exercise is what you use for your RMR, non-exercise physical activity, and thermic effect of food. Energy availability below what’s required to maintain those functions might lead to weight loss, though not always. Over time, your body needs to find other sources of energy, prioritize essential functions like movement, and maintain a safe body temperature. This means slowing down bone maintenance, reproductive functions, and other “non-essential” processes.
When the first American College of Sports Medicine position stand on the Female Athlete Triad came out in 1997, disordered eating was described as the cause for LEA and part of the Triad. However, the Triad and (more recently) RED-S have been updated to state that LEA can be with or without disordered eating or eating disorders. It can also be caused by normal, healthy eating patterns that are outweighed by ultra-endurance training and related types of exercise, resulting in unintentional or inadvertent undereating.
A healthy eating plan that includes energy-dense foods can help support your body’s energy needs to perform its normal day-to-day functions plus the energy requirements for exercise.
LEA impacts on health and performance
For women, the connection between LEA, reproductive function, and bone health is well-supported by research. While less studied in men, there’s evidence that LEA can also lead to suppressed reproduction (low testosterone, decreased sperm number, and reduced motility) and impaired bone health as well. In a normal condition, your body breaks down damaged bone and replaces it with new bone to maintain bone strength and adapt to loading from exercise and other daily physical activity. In a LEA state, the formation of new bone is slowed. In addition, the decrease in estrogen and other reproductive hormones with LEA can also result in even more bone breakdown. More breakdown and less formation together lead to bone loss, increasing your risk for osteoporosis and bone injuries like stress fractures.
LEA can lead to decreased muscle mass too. When your body shifts to preserving essential functions, it doesn’t have access to enough energy to support the muscles and maintain their size. It can also develop a resistance to growth hormone, which means that even though it’s produced by your body, you can’t use it to build new bone and muscle cells as they break down. LEA might also reduce physical performance by leading to decreased muscular strength and endurance, which might also increase your risk for musculoskeletal injury.
LEA has been proposed to decrease immune system function. In athletes with LEA, researchers have found higher rates of the common cold and other upper respiratory tract infections. This might be related to how the immune system can be suppressed with high levels of endurance exercise over long periods of time, leading to LEA. However, the research in this area is thin, and researchers haven’t controlled for other factors that might cause illness, so it’s hard to say if LEA is the exact cause.
Prevent Triad and RED-S
Knowing the signs of the Triad and RED-S is the first step. For active females, the first sign is often irregular or absent menstrual cycles, which can be a signal that you have LEA. For both males and females, decreased athletic performance, fatigue, depression symptoms, irritability, and decreased concentration and coordination can be signs of LEA. In turn, LEA can result in the health impairments outlined in the Triad and RED-S syndromes.
It’s also important to know that RED-S/LEA isn’t always caused by disordered eating, so it’s incorrect to think, “I eat normally so RED-S can’t be the problem.” Undereating can be unintentional, due to things like not finding time for lunch during a busy day at work or school or not knowing how many calories and which types of foods your body needs to support your health and exercise. Disordered eating describes abnormal eating patterns that, while not full-blown psychological illnesses diagnosable as eating disorders, still result in caloric restriction and can lead to LEA. Behaviors such as skipping meals, frequent dieting (yo-yo dieting), preoccupation with being thin that leads to restricting food intake, extreme picky eating, and using exercise, fasting, or other methods to make up for feelings of guilt after eating certain foods are all considered disordered eating.
Eating disorders are psychological conditions with specific diagnostic criteria. Not everyone who displays disordered eating behaviors has an eating disorder.
Eat energy-dense foods
LEA is a complex condition that can be caused by a whole host of factors. Endurance athletes can develop LEA if they don’t eat enough energy-dense foods that are higher in carbohydrates and fat. While whole fruits and vegetables are high in vitamins, minerals, and fiber, they don’t provide much energy for your body to use. In addition to fruits and vegetables, include energy-dense foods such as lean proteins, whole grains, starchy vegetables, and unsaturated fats in your eating plan.
- Lean proteins include fish, poultry, beans, nuts, and yogurt.
- Whole grains and starchy vegetables include oats, brown rice, beans, and potatoes.
- Unsaturated fats include olive and peanut oils, peanut butter, avocados, fish, and nuts.
For endurance athletes, eating enough fat and carbohydrates is crucial. Fat provides the highest number of calories per gram (that is, more bang for your buck), and your body can store enough fat to sustain exercise at low intensity for long periods of time. Though they have fewer calories per gram than fat, carbohydrates provide quick energy for higher-intensity exercise and help support fat use during activities of longer duration.
Get help
Consult a Registered Dietitian (RD) to help design a balanced eating plan that supports your energy needs and fits any dietary restrictions you might have. This is particularly helpful when eating a plant-based or vegetarian diet, where it can be tough to identify energy-dense foods.
If you’re suffering from an eating disorder, getting psychological help is also critical. Remember, seeking mental health care will not normally affect your security clearance. It’s a clear course of action, a sign of sound judgment, and a recognized, positive step during the personnel vetting process.
