When “Eating Healthy” Isn’t Enough: Unintentional Underfueling in Female Athletes
When athletes hear the word underfueling, many picture a deliberate diet: skipping meals to lose weight, cutting out entire food groups, or intentionally trying to eat less.
Sometimes that is what is happening. Often, it is not.
One of the most common patterns I see is an athlete who believes she is eating well—and, from a food-quality standpoint, she often is. She may prioritize protein, avoid fast food, and carry a water bottle everywhere. But she also has school or a full-time job, a commute, a late practice, and very few real opportunities to eat. Breakfast is small. Lunch is light. She gets through the afternoon on caffeine or a snack, then goes directly into several hours of training. No single choice appears concerning. It is the accumulated gap between intake and demand that becomes the problem.
Underfueling is a mismatch, not a character flaw
Low energy availability occurs when the energy left after exercise is not sufficient to support the body’s other essential work. Training is only one demand. The body also needs energy to maintain bone, reproductive function, immunity, cardiovascular health, tissue repair, temperature regulation, cognition, and normal daily life.
This mismatch can happen without an eating disorder and without any intention to restrict food. Common causes include:
Long gaps between meals because of school, work, rehearsals, or commuting
Underestimating how much energy a high training load requires
Trying to “eat clean” so rigidly that meals become too small or not energy-dense enough
Reduced appetite before or after intense evening training
Fear that carbohydrates, convenience foods, or late-night eating are inherently unhealthy
Increasing training without increasing food
Relying on protein-focused foods while overlooking total energy and carbohydrate needs
Financial, family, cooking, or food-access limitations
The problem is not that the athlete lacks discipline. In many cases, the athlete is exceptionally disciplined. The problem is that her routine does not consistently replace what training takes out.
What underfueling can look like
The body is remarkably good at compensating—until it cannot continue doing so without consequences. Early signs are easy to dismiss as normal parts of being busy or training hard:
Feeling depleted, heavy, or unusually flat during practice
Persistent soreness or slower recovery
Difficulty concentrating, irritability, or mood changes
Feeling cold when others do not
Sleep disruption, even when exhausted
Increased reliance on caffeine
Recurrent illness or nagging injuries
Declining strength, stamina, coordination, or training quality
Changes in menstrual frequency, regularity, or flow
Unexplained weight change
Athletes do not always experience underfueling as obvious hunger. By the time they recognize a problem, they may have normalized fatigue, soreness, or declining training quality as part of being busy and committed. When those changes become routine, it is worth looking beyond the training program and asking whether the athlete has enough energy available to benefit from it.
Over time, problematic low energy availability may contribute to Relative Energy Deficiency in Sport, or REDs. REDs describes the broader health and performance effects that can occur when an athlete’s energy intake repeatedly fails to support both exercise and normal physiological function. The consequences may involve bone health, menstrual and reproductive function, metabolism, immunity, cardiovascular health, mental health, and performance.
A missed period is not the only warning sign, and a regular period does not prove that fueling is adequate. Weight is not a complete screening tool either. An athlete can be underfueled at a stable weight, and someone whose weight changes is not automatically underfueled. The pattern matters.
A simple self-check
*This is not a diagnostic test. It is a prompt to notice whether your routine and your symptoms deserve a closer look.
Ask yourself:
Do I regularly go more than four or five waking hours without eating?
Do I often begin training hungry, lightheaded, or aware that I have eaten very little that day?
Do I frequently finish a hard session without eating afterward?
Am I trying to perform through the traditional dinner window without moving that meal earlier?
Am I exhausted by the end of practice or heavily dependent on caffeine to get through the day?
Has my performance, motivation, strength, or ability to recover changed?
Am I frequently sore, sick, cold, irritable, or unable to concentrate?
Have I had repeated injuries, especially bone stress injuries?
Has my menstrual cycle become irregular, less frequent, absent, or otherwise noticeably different?
Am I increasingly anxious about food, weight, eating late, or foods I consider “bad”?
One “yes” does not establish a medical problem. Several recurring “yes” answers are a reason to stop assuming that feeling depleted is simply part of being an athlete.
When a routine adjustment may be enough—and when to seek support
Start by adjusting your routine when:
The problem appears to be a predictable scheduling gap, symptoms are mild or occasional, and eating more consistently improves how you feel and train. Start by adding structure:
Eat consistently across the day rather than saving most food for the evening.
Include carbohydrate as well as protein around training.
Create a substantial afternoon meal when practice replaces dinner.
Keep convenient foods available for the car, work, school, or the rehearsal space.
Plan a simple recovery option after late training, even when a full meal is unappealing.
Seek professional support when:
Seek support from a sports dietitian and an appropriate medical professional when symptoms persist despite routine changes or you notice menstrual changes, recurrent bone stress injuries, persistent fatigue, significant or unexplained weight change, declining performance, repeated illness, dizziness or fainting, gastrointestinal symptoms that interfere with eating, or growing anxiety and rigidity around food or body weight.
Urgent symptoms—including fainting, chest pain, severe weakness, confusion, or concern for immediate medical safety—require prompt medical evaluation.
An athletic trainer, physician, therapist, and sports dietitian may each see a different part of the picture. The strongest support is often collaborative. Asking for help does not mean you have failed to manage your nutrition. It means you are treating fueling as part of your health and performance plan.
Enough is part of “healthy”
Food quality matters. So do timing, access, flexibility, enjoyment, and total intake.
An athlete can eat nutrient-dense foods and still not eat enough. She can prioritize protein and still lack the carbohydrate needed to train well. She can be committed, fit, and successful while her body is quietly absorbing the cost of a mismatch.
The better question is not simply, Am I eating healthy foods?
It is: Am I eating enough, often enough, to support what I am asking my body to do?
About the author: Nina Szemis, MEd, ATC, CFSC, is a certified athletic trainer with more than 15 years of experience in sports medicine and athletic performance, with particular expertise in professional dance and entertainment medicine. Her work integrates sports medicine, strength and conditioning, recovery, and athlete education.
This article is for general educational purposes and is not a substitute for individualized medical or nutrition care.