In a world that praises discipline, leanness, and “pushing through,” many women—especially active women—are unintentionally underfueling their bodies. Maybe you’re training for a marathon, hitting the gym five days a week, or just trying to “lean out.” But what if I told you that your body might be giving you subtle (or not-so-subtle) signals that you’re not eating enough?
I know this struggle firsthand.
A few years ago, I was hiking 7–10 miles a day, doing both CrossFit and rock climbing four times a week, and training a few Personal training clients every week. I was constantly moving, training hard, and challenging my body. And yet, I truly believed that 1,900 calories a day was plenty to meet my energy needs.
For reference, I’m 5’10” and 160 lbs—a strong, active woman. Looking back, it was absurd that I thought I could fuel that level of activity on such low intake. My body was screaming for more food, but I ignored the signs, convinced that I was “eating enough” and doing what I needed to stay lean and fit.
That’s where Relative Energy Deficiency in Sport (RED-S) comes in. Originally recognized as the Female Athlete Triad (focusing on bone health, menstrual dysfunction, and energy availability), RED-S expands on this, showing that low energy availability affects nearly every system in the body—hormones, metabolism, digestion, immunity, cardiovascular function, and even mental health.
You don’t have to fit the telltale signs of the Female Athlete Triad (fatigue, menstrual dysfunction, and poor bone health) to be underfueling. RED-S affects a much wider spectrum of active women—many of whom look “healthy” on the outside but are struggling internally.
What is RED-S?
RED-S occurs when the energy (food) you take in isn’t enough to support both your training and the baseline functions your body needs to survive—things like hormone production, muscle repair, and cognitive function. And it doesn’t just happen to elite athletes. It happens to everyday women who exercise regularly, even recreationally, and don’t realize they’re running on an energy deficit.
You don’t have to feel like you’re starving for this to be a problem. Many women eat what they think is “enough” (or even feel full) but are still consistently underfueling relative to their activity level. This is especially common in endurance athletes, women who have dieted for long periods, or those who eat in a way that prioritizes “clean” or “low-calorie” foods without considering overall intake.
Signs You Might Be Underfueling
RED-S isn’t always obvious. You might be underfueling if you experience:
✅ Fatigue that doesn’t go away – Feeling exhausted, even when getting enough sleep.
✅ Frequent injuries or nagging pain – Stress fractures, joint pain, or slow recovery.
✅ Irregular or missing periods (Amenorrhea) – Not just a “perk” of training hard—this is a major red flag. Losing your period (or having it become irregular) is one of the biggest indicators that your body is in a state of low energy availability.
✅ Cold hands and feet – A sign that your body is downregulating metabolism.
✅ Brain fog and low motivation – Trouble focusing or feeling unmotivated despite loving your sport.
✅ Poor performance despite training harder – A telltale sign your body isn’t recovering properly.
✅ Digestive issues – Bloating, slow digestion, or feeling “off” after meals.
✅ Increased anxiety or irritability – Your brain needs fuel, too.
For me, it was a mix of these. I was training more than ever, but I just couldn’t seem to PR my lifts. Instead, I had nagging injuries that required me to see multiple PTs to fix my hip flexor pain. I’d move my body nearly every waking moment, but the idea that I could need more than 2000 calories was absurd (in my mind). I’d convince myself I was “just a little tired” or “needed more coffee,” when in reality, my body was screaming at me to wake up and eat more.
Why This is So Common in Women
Women are more susceptible to underfueling for a few key reasons:
Social Conditioning – From a young age, women are often taught to eat less, shrink, and prioritize thinness over strength or performance. Many women underfuel not out of intention but because they believe they’re “eating clean” or “being healthy.”
Diet Culture & Misinformation – There’s a massive gap in education around what active women actually need nutritionally. A 1,200–1,500 calorie diet might be enough for a toddler—not a grown woman who lifts, runs, or does any form of high-output exercise.
Misunderstanding of Energy Needs – Women often assume they need to earn their food through exercise rather than fueling for exercise. Many also don’t realize that hormonal fluctuations (hello, luteal phase!) increase caloric needs.
Fear of Weight Gain – The idea that eating more will automatically lead to weight gain keeps many women in a cycle of chronic underfueling, despite the fact that proper fueling actually helps metabolism, muscle retention, and body composition.
I can’t tell you how many times I hesitated to eat more, convinced it would make me “lose progress.” But the truth? Once I started fueling properly, my performance improved, my recovery sped up, and my energy levels completely transformed.
What Can You Do About It?
If you suspect you might be underfueling, here’s where to start:
✅ Track Your Intake (Without Obsession) – Logging food for a few days can provide insight into whether you’re getting enough energy and macronutrients. Key focus areas: carbs, protein, and overall calories.
✅ Prioritize Carbohydrates – Many women under-eat carbs out of fear or misinformation, but carbs are crucial for hormone health, performance, and recovery.
✅ Listen to Your Body – Hunger isn’t the only signal. If you’re experiencing RED-S symptoms, consider increasing intake before hunger kicks in.
✅ Support Your Cycle – If your period is irregular or missing, take this as a sign—not something to brush off.
✅ Work with a Coach or Professional – It can be hard to see the full picture on your own. Having a coach who understands RED-S and female nutrition can help you fuel properly without falling into extremes.
Final Thoughts
Your body isn’t meant to run on empty. Underfueling isn’t a badge of honor—it’s a warning sign. If you’re active, your body needs energy to keep you strong, resilient, and thriving.
I learned the hard way that doing more without eating more isn’t sustainable. Once I shifted my mindset from “eating less” to fueling more, everything changed—my strength, my endurance, my recovery, even my mood. And I want that for you, too.
If you’re ready to stop second-guessing your nutrition and start fueling properly, apply for coaching with me at Risk Nutrition Co. Let’s get you feeling your best—strong, fueled, and thriving.
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