This past month, I counseled over 80 sessions, and the number one mistake I see teens making is trying to “lean out” or lose weight by making calorie restriction (dieting) a long-term strategy. They are not giving themselves ample calories to support their training and their growth. Out of all the nutrition and food-related posts and conversations on social media, you won’t find this information in most people’s “what I eat in a day” posts. If I had to give one piece of advice to young people, athletes, and everyday gym-goers looking to improve body composition, this would be it: Make sure you get adequate energy and nutrients to support training AND growth. Let’s dive into why.

Low Energy Availability (LEA) and RED-S

Athletes and fitness enthusiasts are often encouraged to push their limits with both performance and body image – the pressures of a sport, or concern for being thin, which does not translate directly to performance. We see it in challenges like 75 Hard: train harder, follow a meal plan or structured diet, and drink a gallon of water. However, in the pursuit of excellence and in the name of “health”, many unknowingly put themselves at risk of low energy availability (LEA)—a state where the body’s energy intake is insufficient to support both exercise and essential physiological functions such as bone formation when accrual of bone is most significant at 12 – 14 years of age. When this condition persists, it can lead to what’s called Relative Energy Deficiency in Sport (RED-S). This syndrome affects not only elite athletes but also recreational gym-goers and fitness enthusiasts.

What is RED-S?

RED-S, first described by the International Olympic Committee in 2014, expands on the Female Athlete Triad and acknowledges that energy deficiency affects all athletes, regardless of gender. This condition arises when an individual consistently consumes fewer calories than their body needs to support both training and vital functions like metabolism, immune health, and hormonal balance. Over time, the body starts prioritizing survival over performance, leading to widespread physiological consequences. The problem compounds when the person cannot discern that these symptoms are a result of low energy availability and place blame on a host of other things.Athletes describe fatigue, gastrointestinal issues, missed periods, and an unhealthy relationship with food. Unknowingly, it’s related to their food intake. While they think they are doing the right thing by being in a calorie deficit, it is actually working against them.

Signs and Symptoms of RED-S

Recognizing the early signs and symptoms of RED-S is crucial for preventing long-term health issues. Many athletes won’t connect the dots of their symptoms, or simply cannot due to calorie restriction. That’s why it is important for parents and coaches to be aware of athletes behavior and patterns.

Here are some key indicators:

1. Chronic Fatigue and Low Energy

One of the earliest and most noticeable symptoms of RED-S is persistent fatigue. They often attribute it to being exhausted from intense training practices or they can’t recover and get ahead of it. Athletes may find themselves feeling sluggish, struggling to complete workouts, or requiring longer recovery periods.

2. Frequent Illness and Injury

A compromised immune system can make individuals with RED-S more susceptible to colds, infections, and injuries such as stress fractures and tendonitis. Healing from injuries may also take longer than usual. The last thing they want to hear in an already short season that they have prepared so heavily for.

3. Hormonal Imbalances

For women, RED-S can lead to irregular or missing menstrual cycles (amenorrhea). I hear young girls tell me they don’t mind missing their period but the consequences can lead to low bone mineral density, even infertility. Meanwhile, men may experience reduced testosterone levels, resulting in decreased muscle mass, libido, and energy.

4. Poor Bone Health

Low energy availability impairs bone formation, increasing the risk of stress fractures and ultimately osteoporosis, particularly in weight-bearing sports or high-impact training routines. Injury will set an athlete back considerably, especially with a fracture. If a teen is restricting calories, they could be missing the pro-bone vitamins and minerals.

5. Gastrointestinal Issues

Chronic underfueling can slow digestion and cause bloating, constipation, or discomfort, often misattributed to food intolerances rather than inadequate energy intake. The majority of patients I see are related to gut health and bloating. One of the first things I look for is if they have very little diversity in their diet. Typically, I find this in athletes following a very structured meal plan from a trainer or from the internet.

6. Mood Disturbances

An inadequate calorie intake can lead to irritability, anxiety, and even symptoms of depression due to disruptions in neurotransmitter function and stress hormone regulation. If you find yourself annoyed at the littlest things, this may be a sign.

7. Declining Performance and Recovery

Despite training hard, athletes with RED-S may experience performance plateaus or even declines in strength, endurance, and coordination. Recovery times between workouts may be longer, and motivation to train may dwindle. 

Who is at Risk?

While RED-S is most commonly associated with endurance athletes (runners, cyclists, swimmers) and aesthetic-focused sports (gymnastics, figure skating, bodybuilding), anyone engaging in regular intense training without sufficient fueling is at risk—including recreational gym-goers who cut calories excessively or engage in prolonged fasting to maintain a lean physique.

I had a “weight loss coach” who didn’t recognize the signs. I ended up doing some damage to my GI tract and developing some severe intolerances. – client

Preventing and Addressing RED-S

The good news is that RED-S is preventable and reversible with proper intervention. Strategies include:

• Eating enough calories to match training demands, with a balance of carbohydrates, proteins, and fats.
• Prioritizing recovery through adequate sleep, rest days, and low-intensity training when needed.
• Monitoring menstrual cycles and other hormonal indicators in both men and women.
• Paying attention to bone health with sufficient calcium and vitamin D intake.
• Working with a sports dietitian or healthcare provider to ensure optimal energy availability and overall well-being.

Final Thoughts

RED-S is a serious yet often overlooked condition that can impact athletes and fitness enthusiasts of all levels. Recognizing the early warning signs and taking proactive steps to maintain adequate energy intake can help prevent long-term health complications and support sustainable performance gains. Remember, optimal performance starts with fueling your body properly—energy availability is not a luxury, it’s a necessity.

If you suspect you or someone you know may be struggling with RED-S, schedule a call with me to develop a balanced approach to nutrition and training.