Bone Health in Female Athletes: Fueling for Strength

Many female athletes—especially in endurance or aesthetic sports—face hidden threats to their bone health, often rooted in one underlying problem: low energy availability (LEA). When athletes don’t eat enough to support both daily life and training demands, it sets off a domino effect in the body. Hormones get disrupted. Menstrual cycles disappear. And bones do not get enough of the nutrients they need to stay strong.

This isn’t just a theory. It’s well-established science—so much so that it has an official name: Relative Energy Deficiency in Sport (REDs). And one of its most damaging outcomes? Bone stress injuries (BSIs). These range from minor stress reactions to full-blown fractures, and they’re two to four times more common in female athletes than in males. A single BSI can bench an athlete for weeks or even months—and worse, it may signal that deeper damage is already underway.

Let’s break down how nutrition affects bone health, why prevention matters, and what athletes and their support teams can do to protect long-term health and performance

What’s Really at Risk?

Your bones aren’t just rigid support structures. They’re living tissue that constantly breaks down and rebuilds—especially during youth and during physical stress from athletic training. Up to 90% of peak bone mineral density (BMD) is built by age 18, and peak BMD is reached by the age of 30. That means what happens in those early years—fueling, training, recovery—sets the stage for a lifetime of bone strength or fragility.

When athletes don’t eat enough calories (energy) to support bone remodeling, trouble starts. And it can escalate fast. LEA—even for just 4–5 days—has been shown to disrupt hormones that control menstruation and bone health. Chronic LEA leads to lower BMD and increases the risk of injury.

Fuel First: Energy Availability Matters Most

The most important nutrition goal for female athletes? Make sure you’re eating enough—especially relative to your training load.

Energy Availability (EA) refers to how much energy your body has left after training to support basic functions like hormone production, immune health, and, yes—bone rebuilding. EA below 30 kcal/kg of fat-free mass per day is considered problematic.

When energy intake is too low:

• Hormones like estrogen and IGF-1 drop.

• Menstrual cycles can stop (a sign of disrupted reproductive health).

• Bone turnover becomes imbalanced—meaning more breakdown than build-up.

Even if you’re getting your period, you can still have low energy availability and be at risk. That’s why screening and awareness matter.

Don’t Overlook Carbs

Carbs aren’t just for fueling your workouts—they help protect your bones. Recent studies show that restricting carbs before, during, or after exercise can tilt the bone remodeling process toward resorption (breakdown). While the long-term impact is still under study, female athletes should avoid chronically low-carb diets—especially around training windows.

Micronutrient Musts: Calcium + Vitamin D

Two micronutrients rise to the top when it comes to bone health:

• Calcium is the raw material your body uses to build bone.

• Vitamin D helps your body absorb calcium and regulate bone-building hormones.

Female athletes should aim for:

• 1,000–1,500 mg/day of calcium

• 1,000–2,000 IU/day of vitamin D

From Prevention to Performance

Because bone damage builds slowly and can take years to repair, prevention is the best strategy. Working in conjunction with your primary care physician and ideally a sports dietitian, here's what a proactive plan should include:

Primary Prevention (Fuel Early, Fuel Often):

• Build a strong base of knowledge around REDs and fueling.

• Work with a sports dietitian on fueling strategies that support both training and recovery.

• Educate coaches, parents, and teammates so they can spot signs early.

Secondary Prevention (Catch It Early):

• Track more than just menstrual cycles—watch for low mood, weight loss, fatigue, and recurrent injuries.

• Use tools like the Female Athlete Triad Cumulative Risk Assessment or the IOC REDs CAT2 to screen for warning signs.

• Don’t wait for a fracture to act. Even subtle changes in mood, energy, or health matter.

Tertiary Prevention (Address Existing Issues):

• For athletes with low BMD or repeat BSIs, restoring regular cycles and fueling adequately can help.

• In more severe cases, medical treatments like transdermal estrogen may be considered under medical supervision—but only after nutrition and training are addressed.

• Plyometric and strength training may also help stimulate bone growth.

Performance Is a Long Game

For female athletes, building strong bones isn’t just about preventing injury—it’s about maximizing performance and staying in the game for the long haul. Bone damage caused by under-fueling isn’t just hard to spot—it’s hard to fix. But the good news? It’s highly preventable. And protecting your bones now means you can stay active, strong, and independent later in life—without worrying about brittle bones slowing you down.

Fuel well. Train smart. And if you’re unsure whether you’re doing enough, talk to a professional—before a stress fracture makes the decision for you.