Bone Stress Injury Prevention: 7 Nutrition Red Flags Athletes Overlook

Use this guide to prevent bone stress injuries and stay healthy.

Bone stress injuries (BSIs) which include bone stress reactions and stress fractures, are often linked to underlying nutrition gaps. The challenge is that the warning signs are subtle and typically appear weeks to months before an actual injury develops. When these early indicators are missed, they can progress into a more serious bone injury that can take an athlete out of training for a while.

Many of these red flags are subtle and easily overlooked, especially in athletes who look strong, healthy, and are performing well. Recognizing and addressing these warning signs early can significantly reduce the risk, and help prevent weeks or even months of missed training and competition.

If you’ve experienced a stress fracture before, reducing risk factors is even more important to prevent another bone injury. The risk of a repeat bone injury is highest within the first year of recovery. Being aware and proactive can help prevent more serious injuries and unnecessary time away from sport.

Here are the most commonly missed nutrition-related risk factors and what to do about them.

1. Low Energy Availability (Even Without Weight Loss)

Low energy availability (LEA), occurs when your body uses more energy than you consume through food. It can unknowingly happen when workout intensity increases but the food intake stays the same. Some individuals might even see an increase in weight due to an increase in strength but still don’t consume enough food. Food intake needs to be adjusted based on: workout duration, intensity, routine movements (walking) and normal body functions. If there isn’t enough food to cover all of these essential functions, an energy gap develops. There is food energy available for workouts but not other important body functions. During this time, your body prioritizes exercise and movement, even in a low energy state, and downregulates all other non-essential functions which are important for bone health.

In a low energy available state, these functions are downregulated:

Sex hormone production is suppressed (estrogen, testosterone)
Appetite hormones are poorly regulated (ghrelin and leptin)
Bone remodeling delayed
Muscle growth and repair is decreased
Brain function is suppressed (difficulty focusing)
Stomach issues are more prevalent (bloating, constipation, diarrhea)

Your weight can be stable. Performance can look fine. But your bones and the rest of your body do not have the required energy to recover.

LEA is paramount to the International Olympic Committee’s model of Relative Energy Deficiency in Sport (RED-S)(Mountjoy et al., 2018) and is one of the strongest predictors of bone injury risk (Tenforde et al., 2016). In fact, research shows that bone health can be compromised in as little as five days of underfueling (Papageorgiou et al., 2017).

Common warning signs of low energy availability

Skipping meals or snacks due to busy schedule
Long gaps between meals (>4–5 hours)
No carbs/protein before or after workouts
Fear of eating more on rest days
Waking up hungry
Lightheadedness, irritability, poor focus
Low appetite despite heavy training (this can be a sign of low ghrelin levels, a hormone responsible for appetite regulation)
Gastrointestinal issues (bloating, constipation or diarrhea) can be a sign the body does not have enough energy to digest food

🚩 Common oversight by athletes: Assuming LEA only exists if weight is dropping. However, increased training intensity, and not just weight loss, drives the injury.

How to fix it

Eat often, every 3–4 hours consistently
Add carbs + protein before and after training
Increase intake on heavy training days and recovery days
Work with a sports dietitian to calculate estimated energy needs
Screen for RED-S if recurrent injuries are present

2. Chronically Low Calcium Intake

Many athletes assume they’re “covered” because they eat healthy, but calcium intake is often overlooked.

Research in military recruits and runners shows low calcium intake is associated with higher stress fracture rates (Lappe et al., 2008; Nieves et al., 2010). One study found that consuming just one cup of skim milk daily was associated with ~62% lower stress fracture incidence.

Risk factors

Avoiding dairy without fortified alternatives
No daily calcium source
Intake below ~1,000 mg/day (athletes often need 1,200–1,500 mg/day)

🚩 Common miss: Not accounting for daily consistency.

How to fix it

Aim for 3–4 calcium-rich servings daily:

Milk or fortified plant milk
Greek yogurt
Cottage cheese
Calcium-set tofu
Fortified cereals
Canned salmon with bones

If dairy-free, ensure fortified alternatives are used daily – not occasionally.

3. Low Vitamin D Status

Vitamin D is essential for calcium absorption and bone mineralization. The best source of Vitamin D is from the sun. Athletes can still have low levels even if they train outdoors.

Low Vitamin D levels are associated with significantly higher bone stress injuries (Shimasaki, 2020, Ruohola, 2006). Vitamin D helps the body absorb calcium. Signs of vitamin D deficiency are subtle and include: bone pain, poor mood or low energy.

Risk Factors

No winter supplementation
Limited fortified foods
Indoor sport or early/late training
Persistent fatigue

🚩 Common miss: Waiting for bone pain or other symptoms instead of screening proactively.

How to fix it

Check Vitamin D levels checked annually
Consider 1,000–2,000 IU/day during low-sun months (based on labs and provider guidance)
Pair vitamin D intake with calcium

4. Protein Intake Too Low for Training Load

Protein isn’t just for muscle, it supports collagen synthesis and bone matrix formation.

Research shows inadequate protein intake negatively affects bone turnover (Heaney & Layman, 2008).

Risk Factors

Intake below ~1.2 g/kg/day in high-performing athletes
Most protein eaten at dinner only
Poor post-workout recovery nutrition
Over-reliance on supplements instead of whole foods

🚩 Common miss: Meeting “minimum” intake but not optimal for training with high quality sources.

How to fix it

Target 1.6–2.0 g/kg/day during heavy training
Distribute protein evenly (20–40 g per meal/snack)
Include protein within 60 minutes post-workout
Choose high quality protein sources such as beef, chicken, fish, dairy or plant-based soy or quinoa
For plant-based athletes: legumes, grains, soy, nuts, and seeds

5. Iron Deficiency (With or Without Anemia)

Fatigue is often normalized in sport however iron deficiency is common in athletes with bone stress injuries. Iron deficiency can present as persistent fatigue and low energy, despite adequate fueling.
A 2017 study in Clinical Journal of Sport Medicine found iron deficiency frequently present in female athletes with BSIs (Tenforde, 2017).
Iron deficiency often coexists with low energy availability and RED-S.
Risk Factors
- Low ferritin (even if hemoglobin is normal)
- Regular menstrual cycle (longer duration or heavy bleeding)
- Plant-based diet without adequate iron-rich foods
- GI intolerance to iron-rich foods
🚩 Common miss: Treating iron without addressing underfueling.
How to fix it
- Screen ferritin (not just hemoglobin)
- Increase iron-rich foods (red meat, poultry, beans, lentils, tofu, fortified grains)
- Pair plant iron with vitamin C
- Address overall energy intake alongside supplementation
- Supplement, if recommended by physician

6. Subclinical Disordered Eating

An athlete doesn’t need a diagnosed eating disorder to increase bone injury risk. There can be disordered behaviors that prevent an athlete from eating enough food to support exercise.

Research shows disordered eating behaviors independently increase stress fracture risk (Torres-McGehee, 2009).

Risk Factors Related to Disordered Eating

Rigid food rules
Anxiety about rest days
Avoiding carbs or fats
“Saving calories”
Refusing team meals
Excessive focus on “clean eating”
Increasing exercise but not adjusting food intake

🚩 Common miss: Waiting until behaviors are severe enough for diagnosis.

How to fix it

- Normalize adequate fueling as performance-supportive
- Screen early when injuries recur
- Refer to a sports RD and mental health professional
- Shift culture from weight-focused to performance-focused

7. Menstrual Changes Framed as “Normal”

Amenorrhea or irregular cycles are not aligned with fitness.

Menstrual dysfunction is strongly associated with increased stress fracture risk and low bone mineral density (Bennell, 1997; Nattiv, 2013).

Risk Factors

Cycles >35 days apart, also called Oligiomenorrhea
Loss of period during heavy training
Delayed menarche
Hormonal contraception masking irregularity

🚩 Common miss: Referring to missed cycles as “normal for the sport.”

How to fix it

- Track natural cycles
- Investigate missed periods immediately
- Increase energy availability
- Coordinate care with a sports medicine provider

Staying Healthy

Athletes rarely develop bone injuries from one nutrient deficiency.

They develop them from multiple small fueling gaps that persist over time:

Slight underfueling
Slight calcium shortfall
Slight protein inadequacy
Slight iron depletion

Practical Screening Question

Ask yourself (or your athlete):

“Am I fueling enough to support today’s training and tomorrow’s bone recovery?”

If the answer isn’t a confident yes, it’s worth evaluating.

Early intervention and identification of risks can help athletes prevent injuries that can disrupt a season.

If you’re a runner, athlete, or parent of a young athlete looking for personalized fueling guidance, Amy Stephens offers in-person and virtual nutrition counseling.

References

Bennell, K. L., Malcolm, S. A., Thomas, S. A., Wark, J. D., & Brukner, P. D. (1997). Risk factors for stress fractures in female athletes. Medicine & Science in Sports & Exercise, 29(7), 949–957. PMID: 9243486

Crunkhorn ML, Etxebarria N, Toohey LA, Charlton P, Watson K, Drew M. The Natural History of Bone Stress Injuries in Athletes: From Inception to Resolution. Sports Med. 2025 Oct;55(10):2415-2428. doi: 10.1007/s40279-025-02280-9. Epub 2025 Jul 28. PMID: 40721688; PMCID: PMC12513886.

Heaney, R. P., & Layman, D. K. (2008). Amount and type of protein influences bone health. Journal of the American College of Nutrition, 27(5 Suppl), 530S–536S. PMID: 18838456

Lappe, J. M., Stegman, M. R., & Recker, R. R. (2008). The impact of lifestyle factors on stress fractures in female Army recruits. Journal of Bone and Mineral Research, 23(5), 741–749. https://doi.org/10.1359/jbmr.080102 PMID:18241246

Mountjoy, M., Sundgot-Borgen, J., Burke, L., Ackerman, K. E., Blauwet, C., Constantini, N., Budgett, R. (2018). IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. British Journal of Sports Medicine, 52(11), 687–697. https://doi.org/10.1136/bjsports-2018-099193 PMID: 29773536

Nattiv, A., Loucks, A. B., Manore, M. M., Sanborn, C. F., Sundgot-Borgen, J., & Warren, M. P. (2013). American College of Sports Medicine position stand: The female athlete triad. Medicine & Science in Sports & Exercise, 45(10), 1867–1882. https://doi.org/10.1249/MSS.0b013e3182a1eaa3 PMID: 23832102

Nieves, J. W., Melsop, K., Curtis, M., Kelsey, J. L., Bachrach, L. K., Greendale, G., Sowers, M. F., & Sainani, K. L. (2010). Nutritional factors that influence change in bone density and stress fracture risk among young female cross-country runners. PM&R, 2(8), 740–750. https://doi.org/10.1016/j.pmrj.2010.04.020 PMID: 20709302

Nieves, J. W., et al. (2010). Calcium and stress fracture risk in female recruits. Calcified Tissue International, 87(4), 329–337. PMID: 20617346

Papageorgiou, M., Elliott-Sale, K. J., Parsons, A., Tang, J. C. Y., Greeves, J. P., Fraser, W. D., & Sale, C. (2017). Effects of reduced energy availability on bone metabolism in women and men. Bone, 105, 191–199. https://doi.org/10.1016/j.bone.2017.08.019 PMID: 28847532

Shimasaki, Y., et al. (2020). Vitamin D status and stress fracture incidence in athletes. Journal of Sports Science & Medicine, 19(1), 59–68. PMID: 32009371

Tenforde, A. S., et al. (2016). Low energy availability in athletes: Causes, consequences, and risk factors. Sports Medicine, 46(1), 1–16. https://doi.org/10.1007/s40279-015-0423-6 PMID: 26553498

Tenforde, A. S., et al. (2017). Association of the female athlete triad risk assessment stratification to the development of bone stress injuries in collegiate athletes. Clinical Journal of Sport Medicine, 27(5), 495–502. PMID: 27359220

Torres-McGehee, T. M., et al. (2009). Eating disorders and the female athlete triad among athletes. Sports Health, 1(5), 379–385. https://doi.org/10.1177/1941738109334218 PMID: 23015865

Amy Stephens