If you're an athlete or a very active person and you're experiencing changes in your menstrual cycle, energy, mood, and performance—especially if you eat a restrictive diet— you might be suffering from Relative Energy Deficiency in Sport, also called RED-S.
RED-S, formerly known as the Female Athlete Triad Syndrome, is more prevalent than many might expect. It affects athletes across genders and disciplines but is most common among those who do extensive endurance or aerobic exercise and eat a relatively low-calorie diet, as well as athletes who perform sports where weight and aesthetics are emphasized1 (such as gymnastics, figure skating, dance, or ballet).
RED-S arises from an imbalance between calorie (or energy) intake and energy expended in exercise and other types of daily physical activity. It's caused by insufficient energy available to support essential bodily processes that are necessary for general health, performance, recovery, and reproduction.
In this article, learn about the underlying causes of RED-S, who's at greatest risk, plus solutions to help correct this imbalance in order to support fertility and overall physical and mental health.
In this article:
- Signs and Symptoms of RED-S
- What Causes Relative Energy Deficiency in Sport (RED-S)?
- Hormonal Disruptions Involved in RED-S
- Health Risks Associated with RED-S Syndrome
- The Role of Hormone Replacement Therapy and Birth Control In Managing RED-S
- How to Recover from RED-S
- Key Takeaways On Relative Energy Deficiency In Sport (RED-S)
Signs and Symptoms of RED-S
Depending on how severe the condition is, those suffering from RED-S can experience a range of symptoms, including those that affect their performance, health, and emotional/mental well-being.
Key symptoms and indicators of RED-S can include:
- Menstrual dysfunction: Period problems such as irregular or absent menstrual cycles in females or lack of consistent ovulation. A period that was previously regular, but has been missing for 3 months or more warrants a visit to your healthcare provider as this is a sign of amenorrhea.
- Impaired bone health: Increased risk of stress fractures and osteoporosis due to lower bone mineral density.
- Muscle fatigue and weakness: Decreased muscle strength, poorer performance, and increased injury rates that can result from persistent feelings of fatigue and inability to complete workouts.
- Psychological distress: Mood swings, irritability, poor sleep, and depression can occur, as well as anxiety over performance issues, body image concerns, or the thought of needing to gain weight or train less.
What Causes Relative Energy Deficiency in Sport (RED-S)?
The primary driver of RED-S is an energy imbalance, whether this imbalance happens intentionally or unintentionally.
People with RED-S don't consume sufficient calories to meet their energy expenditure. When their bodies get the signal that there's not enough energy coming in to fuel daily activities, this energy deficit leads to changes in a number of bodily processes—including shifts in hormone production, cognition, metabolic functions, and more.
RED-S can occur for several reasons, often which overlap:
- Increased training loads: During periods of intense training, an athlete’s energy requirements can increase significantly if they're doing lots of exercise. If the increase in food intake doesn't match this rise in energy expenditure, it can lead to an energy deficit.
- Restrictive dieting: Some athletes restrict their calorie intake to achieve a desired body composition, such as a very low percentage of body fat2, low BMI, or a high percentage of muscle mass, or to meet requirements for certain weight categories for competition.
- Imbalance in macronutrient intake: Not only does calorie restriction contribute to RED-S, but restricting certain macronutrients3 (carbohydrates, protein, and fats) can play a role in the development of RED-S, too.
Hormonal Disruptions Involved in RED-S
When people with RED-S experience an energy deficit, this impacts hormonal pathways4 crucial for metabolism, reproduction, immune function, bone health, and more. The body responds to insufficient energy by downregulating various hormonal functions to conserve energy, including:
Alterations in Reproductive Hormones
In females, a significant decrease in energy availability can lead to changes in the menstrual cycle, such as irregular periods with delayed ovulation or amenorrhea (absence of menstruation).
These hormonal changes are caused in part by dysfunction in the HPA axis. Disruptions in the HPA (hypothalamic-pituitary-adrenal) axis can lead to functional hypothalamic amenorrhea (FHA) in some women. FHA accounts for 20–35% of amenorrhea5 and affects over 1.5 million women aged 18 to 44 in the United States. It's most commonly caused by a combination of stress, weight loss, and/or excessive exercise.
HPA axis dysfunction is connected to RED-S because it can cause reduced gonadotropin-releasing hormone (GnRH) pulses, which in turn affect the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland that leads to ovulation.
Some women with RED-S will stop ovulating altogether and may not get their period anymore, while others skip ovulation some months or have delayed ovulation and longer cycles that can lead to fertility struggles.
Slowed Metabolic Rate
RED-S can significantly affect an athlete's metabolic processes, including hunger signals, overall metabolism, and insulin regulation. When the body senses an energy deficit, it may respond by lowering its basal metabolic rate (the amount of energy used every day) as a conservation measure, which can affect energy levels and athletic performance.
Increased Hunger
RED-S can paradoxically increase hunger in some people or suppress appetite in others, depending on how the energy deficit affects their body’s hormonal balance.
- Increased Ghrelin: Ghrelin, the hormone that stimulates appetite, might increase due to energy deficiency, signaling the body to consume more food.
- Decreased Leptin: Conversely, leptin, which suppresses hunger and is secreted by fat cells, might decrease due to reduced body fat levels. This imbalance can lead to increased feelings of hunger and cravings (especially for calorie-dense foods, such as those with sugar, refined carbs, and fat) as the body attempts to prompt energy intake to compensate for the deficiency.
Increased Cortisol
Cortisol, a primary “stress hormone,” is also impacted by an energy imbalance. People experiencing RED-S tend to have higher than normal cortisol levels, potentially leading to poor stress responses and energy usage, as well as other symptoms tied to high stress levels, such as anxiety, mood swings, poor sleep, and cravings.
For example, increased cortisol levels due to stress and overtraining can further complicate appetite signals, as cortisol can stimulate someone's appetite and cravings for high-calorie foods that serve as a quick energy source.
Psychological Factors That Can Contribute to RED-S:
The development of RED-S can also be influenced by psychological factors, such as:
- Body image issues: Athletes, especially in sports that emphasize leanness, can sometimes develop unhealthy body image perceptions that lead to restrictive eating behaviors.
- Performance pressure: High expectations and pressure to perform can lead to overtraining and underfunding, as athletes push their bodies to the limits without adequate energy support.
Health Risks Associated with RED-S Syndrome
RED-D poses significant risks not only to someone's immediate physical health but also to their long-term wellness.
Short-term Risks:
- Menstrual irregularities
- Compromise the immune system, making athletes more susceptible to infections and illnesses
- Poor muscle function, coordination, concentration, and overall athletic performance
- Increased irritability, stress, anxiety, and depression
Long-term Implications:
- Decreased bone density and osteoporosis, with increased risk of fractures
- Disruptions in hormone production, including thyroid hormones, growth hormones, and reproductive hormones
- Altered lipid profiles (such as increased cholesterol) that increase the risk of developing cardiovascular diseases later in life
- Fertility issues that make it more difficult to conceive and maintain a healthy pregnancy
- Metabolic syndrome due to the potential development of insulin resistance, which contributes to type 2 diabetes and high blood pressure
RED-S's Negative Impact on Bone Health:
One major problem that an energy imbalance can cause is decreased bone density. Chronic energy deficits can lead to lower levels of estrogen and testosterone, which are needed for bone formation and maintenance.
When the production of these hormones is reduced, this can increase the risk of osteoporosis and stress fractures, especially among people who are already at risk of injuries if they play contact sports and put lots of stress and strain on their bodies.
Maintaining healthy, strong bones is very important because loss of bone density is not an easy problem to resolve; in some cases, it can even be permanent or take years to fix6. Moreover, RED-S is common among young women in their late teens and early 20s7, which si the same time in which bone density is forming and peaking.
The Role of Hormone Replacement Therapy and Birth Control In Managing RED-S
Hormone Replacement Therapy (HRT) and birth control pills are often used to manage symptoms of RED-S, such as menstrual irregularities, and to protect against bone density loss.
They can work to manage these symptoms of RED-S in women because they're a source of synthetic estrogen that plays a role in regulating the menstrual cycle and contributing to bone density.
With that being said, HRT and birth control pills do not tackle the root causes of RED-S since they aren't able to address the underlying energy deficit that causes this condition. So, while these medications do offer some protection and benefits, they essentially act like a “bandaid” for RED-S in some ways.
- Benefits of HRT and birth control: These treatments can provide symptomatic relief from menstrual disruptions and help maintain bone density.
- Limitations: They do not address the fundamental issue of energy deficiency and can give a false sense of security without solving the underlying metabolic problems. They also won't help improve fertility among women with RED-S who are trying to get pregnant.
How to Recover from RED-S
Recovering from RED-S fast requires a multifaceted approach, including nutrition, exercise, and psychological support. Working with a dietician, along with your health care provider can help you make a recovery quickly.
1. Dietary Changes (Increasing Calorie Intake and Balancing Macronutrients)
Because RED-S is caused by low energy intake, one of the foundational steps in treating this condition is increasing nutrient intake and variety8 in the diet in order to meet someone's daily needs and improve their energy availability (EA).
- Increase caloric intake: Athletes should consume enough calories to match their energy output. To achieve this, someone might need to eat larger portions, eat more frequently (such as every 2-3 hours), and/or to include more calorie-dense foods in their diet, such as more healthy fats and proteins.
EA is the amount of energy left for your body's basic functions after you've subtracted the calories burned during exercise. For female athletes, it's considered optimal if this leftover energy is at least 45 calories per kilogram of fat-free mass9 (FFM) per day.
This means that to meet the guidelines for optimal energy availability, a 130-pound female athlete with approximately 20% body fat should aim for at least 2,124 calories per day, after accounting for the calories expended in physical activities. If possible, consult with a sports dietitian who can help calculate your energy needs based on your sport, phase of training, and current health status.
- Make sure the diet is balanced: Another component of resolving an energy deficit is focusing on the consumption of all three macronutrients10—carbohydrates for energy and replenishing glycogen stores, proteins for muscle repair and recovery, and fats for hormonal balance. Those with RED-S should be sure they're eating a balance of all three macros rather than a very low-carb or low-fat diet, which can sometimes contribute to the hormonal issues that lead to RED-S.
Foods that can help you consume a balance of macros11 include:
- Carbohydrates: whole grains, fruits, vegetables, dairy, and legumes.
- Proteins: lean meats, fish, eggs, dairy, legumes, and tofu.
- Fats: avocados, nuts, seeds, olive oil, oily fish like salmon, eggs, ghee/butter.
For help following a healthy diet, check out my free recipe guide here.
2. Training Adjustments
Adjusting training regimens12 is another important step in addressing an energy deficit.
- Decrease training: People with RED-S usually need to decrease their training load, add more rest and recovery days, and ensure they're fueling themselves properly before and after workouts.
- Take more rest days: Taking periods off from training (such as when not competing or in season), integrating adequate rest days, and focusing on lighter training methods (such as only doing yoga or walking some days instead of intense exercise) can all be helpful.
3. Supplements to Consider
While diet and exercise adjustments are the steps to focus on first when treating RED-S, some supplements can also be helpful for supporting hormonal balance and coping with stress.
- Calcium and Vitamin D: These help to support bone health13, which can be compromised in RED-S. Typically, 1000 mg of calcium and 1000-2000 IU of vitamin D daily, but consider consulting with a healthcare provider for personalized dosing. Because vitamin D3 is best absorbed, especially when combined with vitamin K, pair these two together for the greatest effects (such in my Vitamin D3/K2 drops).
- Iron: Iron helps prevent anemia14, especially if menstrual disturbances or dietary insufficiency are present. Dosage should ideally be determined based on blood iron levels. Typical supplements range from 18 to 65 mg of elemental iron per day. You'll find iron in many prenatal vitamins (including Prenatal Plus), but not in all multivitamins. And in case you're wondering, yes, you can take prenatals even when not pregnant.
- Omega-3 fatty acids: These healthy fats can help reduce inflammation and support brain health, which can be beneficial given the stress of training. A general goal is to aim for a dosage of 1-3 grams of combined EPA and DHA per day, which you'll find in my Omega Plus formula.
- B Vitamins: These vitamins are important for energy production and the repair and maintenance of muscle tissue. A B-complex supplement that provides 100% of the Daily Value (DV) for all B vitamins is generally recommended.
- Magnesium: Magnesium supports muscle function and energy metabolism15 and can assist the body in coping with stress. A general dosage recommendation for magnesium supplementation, such as my Magnesium Plus formula, is 300-400 mg per day.
4. Psychological and Behavioral Approaches
For many people with RED-S, there's a mental and psychological component that's contributing to the condition, such as body image issues, unrealistic desires for weight loss and muscle gain, or even an eating disorder. This is why modifying behaviors is essential for long-term recovery from RED-S.
- Counseling and education: Help from mental health professionals can help someone to change their mindset and behaviors while better managing anxiety.
- Help from coaches and mentors: Coaches can also help encourage healthy attitudes toward training, competition, and body image.
5. Monitoring Symptoms and Adjusting Accordingly
RED-S can improve when someone changes their diet and training schedule, but it can return if the person goes back to living life in a way that results in an energy balance once again. For long-term health, it's beneficial for someone with RED-S to work with knowledgeable healthcare providers to monitor markers like bone density, weight, and heart health.
- Ongoing assessments by professionals: Monitoring can help to keep an eye on health markers and adapt strategies as needed. Among competitive athletes, there should ideally be cooperation between dietitians, physicians, coaches, and psychologists.
- Self-monitoring: The person with RED-S can also monitor their own health by tracking their menstrual cycle, sleep, energy, and mood.
Key Takeaways On Relative Energy Deficiency In Sport (RED-S)
- RED-S (formerly called Female Athlete Triad Syndrome) is a condition that happens in athletes and very active people that is caused by low-calorie intake combined with lots of training, leading to an energy deficit.
- This condition can lead to amenorrhea, bone fractures, and other health issues.
- Early detection of RED-S is critical. Athletes and coaches must be vigilant for RED-S symptoms such as unexplained fatigue, mood issues, poor recovery, and frequent injuries. RED-S symptoms in women can also include irregular menstrual cycles and fertility struggles.
- RED-S syndrome treatment usually requires increased calorie intake, reduced training and energy expenditure, rest, and sometimes psychological support (depending on the unique situation).
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