Food Is Fuel: What Every Female Athlete Needs to Know
Whether you are a 14-year-old competitive swimmer, a university soccer player, or a 45-year-old training for your first half-marathon, food is not something to be managed around your sport. It is how your body shows up, recovers, adapts, and gets stronger. And when you do not eat enough of it, your body pays a price that goes far deeper than a bad training day.
Up to 60% of female athletes are underfueling without even realizing it, according to research by McKendry and Oxfeldt (2023). That is the majority. And the reason so many are in this position is not laziness or carelessness, it is that most girls and women have never been taught what their bodies need when they are training hard.
The gap between how much energy a female athlete burns and how much she eats has a name in sports medicine: Low Energy Availability (LEA). When this gap becomes chronic, it triggers a condition called Relative Energy Deficiency in Sport, or RED-S. The International Olympic Committee updated its consensus on this in 2023, describing RED-S as a syndrome that disrupts function across multiple body systems when the body is running a sustained energy deficit.
The list of what gets impaired is long: metabolic rate, bone health, menstrual function, immune function, protein synthesis, cardiovascular health, mood, and concentration. These are not minor inconveniences. These are foundational systems that your body needs to function.
What Happens When Your Body Does Not Get Enough
When an athlete is not eating enough to cover both her training demands and her basic physiological needs, the body makes hard choices. It starts shutting down processes it deems non-essential in order to protect what it considers vital. Muscle repair slows, hormones go offline, and metabolism drops.
As one recent Virginia Tech Athletics analysis described it: when the body senses an "energy crisis," it goes into survival mode and stops or slows processes like repairing muscle, regulating hormones, and supporting a healthy metabolism. The hormonal consequences are particularly significant for females. Research on RED-S shows that chronic low energy availability disrupts the hormonal pathways that regulate estrogen, which in turn affects bone density. Critically, the bone loss that occurs during periods of LEA is not always fully reversible, even after normal eating and menstruation resume. This matters especially for young athletes who are still building the bone density that should carry them through decades of life.
For adolescent female athletes specifically, the numbers are noticeable. Studies show up to 80% of elite young female athletes and 60% of high school female athletes have at least one symptom associated with RED-S. Teenagers are particularly vulnerable because they are still growing and their energy demands are already high before sport is factored into the equation.
The Performance
A 2024 systematic review published in Nutrition Reviews confirmed that diets adequate in carbohydrates enhance performance in activities that deplete muscle glycogen. When carbohydrate intake is consistently low, the body cannot replenish its fuel stores properly between sessions. That means every workout starts in a slight deficit, recovery takes longer, and the adaptations that come from training, the strength, the speed, the endurance gains, are blunted.
The same principle applies to protein. Research published in the European Journal of Sport Science found that adequate carbohydrate and protein intake are both vital for training adaptation, recovery, and exercise performance. A 2020 meta-analysis found a significant improvement in time-to-exhaustion and time-trial performance when athletes consumed combined carbohydrate and protein, compared to carbohydrate alone. The food on your plate is directly connected to what your body can do under pressure.
Gatorade Sports Science Institute guidelines note that low energy intakes increase risk of fatigue, injury, illness, poor nutritional status, menstrual dysfunction, and impaired performance. For active females, energy intakes below 1,800 calories per day make it difficult to meet the baseline nutrient requirements for energy metabolism, bone health, blood health, and general function. That is before training volume is even factored in.
Why "Eating Less to Stay Lean" Backfires
The belief that a lighter body automatically means a faster or stronger athlete is deeply embedded in sport culture, particularly for women. Gymnastics, rowing, running, cycling, and swimming. For young girls just finding their identity as athletes, it can feel like eating is at odds with performing.
The body composition changes that female athletes often pursue like more muscle and less fat, require adequate fuel to achieve. You cannot build lean tissue without sufficient protein. You cannot train hard enough to adapt without sufficient carbohydrates. And you cannot recover between sessions without enough total energy. Restricting food in pursuit of a certain look does not produce a leaner, more powerful athlete. It produces a fatigued, injury-prone one.
The research on RED-S makes this clear. Even mild, chronic energy deficits can impair hormonal health, bone density, and recovery, leading to long-term performance deterioration, according to Hardie et al. (2022). The damage compounds over time. A stress fracture that might have been avoided with better fueling. A lost season. A hormonal disruption that takes months to correct.
What Proper Fueling Looks Like
There is no single prescription that works for every female athlete, because training load, body size, sport demands, and individual needs vary significantly. But the general framework is this:
Carbohydrates are not the enemy.
They are the primary fuel source for high-intensity exercise, and how much you need depends on how hard and how long you train. For athletes doing around 1 hour of moderate activity per day, such as group fitness or CrossFit-style training, general guidelines recommend 4-6 grams of carbohydrate per kilogram of body weight per day. For those training at moderate to high intensity for 1-3 hours per day, such as preparing for a half-marathon or endurance event, that range moves up to 6- 8 grams per kilogram per day. For pre-competition carbohydrate loading, guidelines suggest 10-12 grams per kilogram in the 36-48 hours before competition. These numbers matter because meeting macronutrient needs can be challenging for highly active individuals, and most female athletes are not coming close to hitting them.
Protein supports repair and adaptation.
Protein requirements for female athletes are roughly 1.6-2.0 grams per kilogram of body weight per day, depending on sport and training phase. Spreading protein intake throughout the day, including after training sessions, supports muscle protein synthesis and recovery.
Fats support hormonal health.
Adequate dietary fat is essential for hormone production, including the sex hormones that regulate menstrual function and bone metabolism. Cutting fat too aggressively disrupts this system.
A Note to Young Female Athletes and the Adults Around Them
If you are a girl in sport reading this: your job is not to be the smallest version of yourself. Your job is to be the strongest, fastest, most capable version of yourself. And that requires food. More than you might think, and probably more than you have been led to believe.
If you are a parent, coach, or trainer reading this: the comments you make about body weight, the meal choices you praise or subtly discourage, the culture you create around food in your sport environment, all of it is heard. Girls are listening. They are forming beliefs about their bodies and food that will follow them for years. Prioritize performance and health. Let body composition be a downstream outcome of excellent fueling and training, not the goal itself.
If you want support figuring out how to fuel for your sport and your life, I would love to work with you. Book in with me and let's build something that actually works.
Sources
The Hidden Struggle: Underfueling Among Division I Female Athletes. https://hokiesports.com/news/2025/11/4/the-hidden-struggle-underfueling-among-division-1-female-athletes
Patterns of Energy Availability and Carbohydrate Intake Differentiate Between Adaptable and Problematic Low Energy Availability in Female Athletes. https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2024.1390558/full
Active Women Need to Fuel Differently from Men. https://www.nutraingredients.com/Article/2025/04/16/active-women-need-to-fuel-differently-from-men/
Fuelling the Female Athlete: Carbohydrate and Protein Recommendations. https://pubmed.ncbi.nlm.nih.gov/34015236/
Nutritional Strategies for Optimizing Health, Sports Performance, and Recovery for Female Athletes and Other Physically Active Women: A Systematic Review. https://academic.oup.com/nutritionreviews/article/83/3/e1068/7712679
