Relative Energy Deficiency in Sport (REDs, including the Female Athlete Triad), and Avoiding Undereating

Section 1: Defining the REDs Model and Low Energy Availability

When there is a mismatch between energy intake (nutrition) and energy expenditure from high athletic demands, the body can become dysregulated. According to the Relative

Energy Deficiency in Sports model (REDs model), female and male athletes subjected to low energy availability caused by inadequate fuel from nutrition may develop poor health and performance outcomes. Symptoms include, but are not limited to, mood swings, fatigue, frequent illness, poor bone health, irregular menstruation, difficulty recovering from athletic activities, and increased risk of injury. Furthermore, there is also a negative impact on athletic performance, including a decrease in muscle strength, endurance, attention/concentration, and coordination. A subset of the REDs model is the Female

Athlete Triad, a medical condition distinguished by low energy availability (which may or may not be brought on by disordered eating), irregular menstruation, and low bone mineral density.

Low energy availability is defined as an imbalance between energy intake (through nutrition) and expenditure (through exercise). The body's overall energy requirements are not satisfied, so there is not enough energy to support the processes that maintain the body in optimal health and allow optimal athletic performance. It can result from overexercising, undereating, and/or improperly balancing energy intake and output. Athletes who participate in endurance sports (i.e., distance running, triathlons, etc), aesthetic sports (i.e., dancing, figure skating, etc), weight-class sports (i.e., wrestling), and sports that associate lean or light body types with better performance are more likely to experience low energy availability. But where do these behaviors stem from? Although they can be tied to personal health or performance goals, often these behaviors reflect deeper cultural pressures that are extremely prevalent in our society. From wanting to achieve society’s ideal body image to our society’s obsession with ‘diet culture,’ these behaviors are often deeply influenced by societal norms and expectations. Low energy availability may be intentional, through nutritional restriction (i.e., disordered eating behaviors or eating disorders) or overexercising. However, inadequate meal planning, exclusion of specific food groups (i.e., carbohydrates, dairy, etc), or increases in training volume or intensity without matching increases in dietary energy intake, can also unintentionally result in low energy availability.

Section 2: How Energy Availability’s Effects on Physical and Mental Health Outcomes and Athletic Performance

Detrimental physical health consequences result from prolonged and/or extreme low energy availability. Among them are compromised metabolism, growth and development, immune system, bone and musculoskeletal health, neurocognitive function, and reproductive function. These adverse health effects may result in a decline in athletic performance, a higher risk of injury, and impaired well-being. The relationship between low energy availability and mental health outcomes is bidirectional: low energy availability may contribute to adverse mental health outcomes and psychological stress, like depression, anxiety, and sleep problems, and mental health problems may also be a risk factor for the development of low energy availability. 

Low energy availability has direct and indirect impacts on athletic performance. Some indirect detrimental effects of low energy availability on performance include being more prone to illness and injury. This is because the endocrine, cardiovascular, reproductive, immune, and metabolic systems are all negatively impacted by low energy availability. Mental clarity, motivation, and physical behaviors are also affected. Direct impacts on athletic performance include decreased ability to respond and recover from training, neurocognitive function (including attention/concentration, decision-making, etc.), power and muscle strength, endurance, and motivation. 

Section 3: How to Spot Red Flags (Physical and Emotional Signs of Disordered Eating)

Disordered eating has both physical and emotional warning signs. Physical signs may include, but are not limited to: compulsive exercise beyond what is beneficial for health and athletic performance; binge eating and purging behaviors; obsession with food and exercise; counting calories; restricting food intake or skipping meals; following special diets and/or avoiding certain food groups; excessive control of food intake; sudden and rapid weight loss; fainting and dizziness; always feeling tired; and irregular or loss of periods in females. Emotional signs may include, but are not limited to: social withdrawal; thoughts of suicide; depressed and irritable mood; anxiety about weight; fear of eating in public; concern about body image or weight; body dissatisfaction and/or dysmorphia (mental health condition where a person obsesses over perceived flaws in their appearance); low self-esteem; feeling out of control around food; and a heightened sensitivity to comments about weight and eating or exercising habits.

Section 4: Fueling the Body with Energy Expenditure from Physical Activity

Proper fueling and well-balanced nutrition are essential to support physical activity as they directly affect performance, energy levels, and recovery. According to the National Collegiate Athletic Association (NCAA), appropriate fueling concerning pre-workout nutrition includes consuming a well-balanced meal 2-4 hours before exercise. This meal should incorporate complex carbohydrates to sustain energy and moderate protein to support muscles. Nutrition while exercising should focus on adequate fluid intake: water should be consumed to replace fluids lost while sweating, reserving sports drinks with carbohydrates and electrolytes for exercise lasting one hour or longer. For long or high-intensity workouts, easy-to-digest carbs like fruit, gels, and bars can provide quick energy and support performance during extended physical activity. For post-workout/recovery nutrition, it is important to consume both carbohydrate types to properly replenish muscle glycogen and protein, allowing muscle protein synthesis within 30 minutes after exercise. According to the United States Olympic Committee Sport Dietitians and the University of Colorado, one-quarter of an athlete’s plate should be composed of lean protein. For low-intensity training days, half the plate should be composed of fruits and vegetables, and the remainder of the plate should be composed of whole grains. For moderate-intensity days, a balanced amount of whole grains and vegetables is recommended. For high-intensity days, more whole grains and fewer vegetables are recommended to support recovery from increased energy expenditure.

Section 5: Recovery from Undereating and Malnutrition 

Recovery from undereating should be guided by a team of health professionals, including a physician/healthcare provider, dietician, and psychologist/therapist. In addition to seeking professional guidance, recovery strategies include: 

• Nutrition: Slowly increase food intake to “regenerate” the digestive system. Begin with easy-to-digest foods to avoid upset stomachs. Consume well-balanced meals and stay hydrated. Listen to your body and eat mindfully: start with small steps and celebrate your progress. 

• Physical activity: Start with light activity, such as yoga, to activate appetite and digestion, and to avoid fatigue and injury.

• Mental health: Work with a therapist or other mental health professional to address underlying causes of underfueling, such as body dysmorphia, anxiety, and depression. Avoid calorie-counting; instead, keep a journal or notebook to track progress and emotions. Form a trusted support system of family members and friends to help throughout the recovery process.

Undereating recovery resources:

• Seek help from your primary care doctor to establish care with a dietitian and mental health provider specializing in disordered eating.

• Contact recovery centers/helplines like NEDA (National Eating Disorders Association) at 866-662-1235 and ANAD (National Association of Anorexia Nervosa and Associated Disorders) at 888-375-7767. 

• Gain knowledge and raise awareness on underfueling via (trustworthy) podcasts, books, and online platforms.

Section 6: Preventing Iron Deficiency and Optimizing Bone Health in Athletes 

Iron deficiency in female athletes is a concern as it can cause impairments in well-being and athletic performance. It is common in female athletes due to blood loss from menstruation, inadequate dietary intake, and/or REDs. To avoid iron deficiency, the National Institute of Health recommends consuming iron-rich foods like lean meat and seafood. Eating these iron-rich foods with vitamin C-rich foods  (i.e., citrus fruits, peppers, and strawberries) increases iron absorption. In addition, iron absorption increases by avoiding consumption of iron inhibitors (foods with phenolic acid and tannins) such as certain herbal teas, coffee, and peppermint. Taking iron supplements under professional supervision and undergoing regular blood tests can further help regulate iron levels. The recommended amount of daily iron intake varies from individual to individual based on factors such as age and gender. For females aged 14-18, the recommended daily iron intake is 15 mg. 

Optimizing bone health through nutrition is essential for maximizing athletic performance and preventing injury. According to the National Institute of Health, sufficient calcium intake helps promote bone mineralization and prevent bone softening. Sources of calcium include dairy, fish, and leafy greens. Similarly, adequate vitamin D intake supports bone health and reduces the risk of fractures and osteopenia/osteoporosis (low bone mineral density). Additionally, vitamin D aids with calcium absorption. Dietary sources of vitamin D include oily fish and egg yolks; however, most vitamin D absorption occurs through the skin from sun exposure. For both calcium and vitamin D intake, respective dietary supplements under medical supervision may be necessary. The recommended amount of daily calcium intake for individuals aged 9-18 is 1,300 mg/day. The recommended amount of daily calcium intake is at least 600 IU/day, but may be higher for female athletes. Proper fueling and nutrition support bone health by preventing the development of REDs/Female Athlete Triad and irregular menstruation, which can have detrimental effects on bone health.

Section 7: Unique Considerations of Special Diets Among Athletes 

- Gluten-free (necessary for those with gluten sensitivity or celiac disease): Excludes foods with gluten and limits carbohydrate options. Deficiency risks: fiber, B vitamins, and iron. It can impact energy levels and lead to low energy availability. Alternatives: quinoa, rice, coconut flour, and buckwheat.

- Vegetarian: Excludes animal flesh, such as meat and fish. Deficiency risks: protein, iron, zinc, and vitamin B12. It can lead to low energy availability and iron deficiency. Alternatives to meat-based proteins: eggs, dairy, plant-based proteins, etc. Consider supplementation guided by a healthcare professional.

- Vegan: Excludes animal flesh, such as meat and fish, and animal products, such as eggs, honey, and dairy products. Deficiency risks: protein, iron, zinc, vitamin B12, and vitamin D. It can lead to low energy availability, iron deficiency, and poor bone health. Alternatives to animal-derived proteins: plant-based proteins like tofu, tempeh, legumes, pea protein, etc. Consider supplementation guided by a healthcare professional.

- Lactose intolerance: Limited intake of dairy products. Deficiency risks: calcium and vitamin D. It can lead to poor bone health. Non-dairy Vitamin D sources: oily fish, egg yolks, and fortified plant-based milks; Non-dairy Calcium sources: tofu, leafy greens, and fortified plant-based milks. Consider supplementation supervised by a healthcare professional when intake from food alone isn’t enough.