When athletes don’t eat enough to match their training, they can develop a condition called Relative Energy Deficiency in Sport (REDs) that affects their health and performance. Researchers looked at 19 different studies involving 759 female athletes to see whether taking medicine or making lifestyle changes (like eating better) works best for fixing this problem. The good news: lifestyle changes like improving nutrition showed real benefits for getting periods back to normal, gaining healthy body fat, and improving energy levels. Medicine showed some promise for bone health but needs more research. Overall, doctors should try lifestyle changes first before considering medicine.

The Quick Take

  • What they studied: Whether giving athletes medicine or helping them eat better and change their habits works best for treating Relative Energy Deficiency in Sport (a condition where athletes don’t eat enough calories for their training level).
  • Who participated: 759 female athletes across 19 different research studies. Most studies looked at non-medicine approaches (15 studies) compared to medicine approaches (4 studies).
  • Key finding: Lifestyle changes—especially eating more and better nutrition—helped athletes gain healthy body fat, get their periods back, and improve their energy levels. Medicine showed some benefits for bone strength but the evidence wasn’t as strong.
  • What it means for you: If you’re an athlete struggling with energy problems or missing periods, working with a nutritionist to eat more calories may be your best first step. Medicine might help with bone health in some cases, but more research is needed. Talk to your doctor about what’s right for you.

The Research Details

Researchers searched five major medical databases for all studies published through July 2025 that tested treatments for Relative Energy Deficiency in Sport. They included only studies that tested real interventions (treatments) and measured whether they worked. They found 19 studies total: 15 that tested non-medicine approaches (like nutrition counseling, eating plans, and behavior changes) and 4 that tested medicine approaches. The researchers then combined the results from multiple studies to see which approach worked better overall.

This type of study, called a meta-analysis, is powerful because it combines information from many smaller studies to get a clearer picture. Instead of relying on one study that might have been done with just a few people, researchers can see patterns across hundreds of participants. In this case, they looked at how much body fat athletes gained, whether their periods came back, and how their hormones changed.

Relative Energy Deficiency in Sport is a serious condition that can cause athletes to lose their periods, develop weak bones, get injured more easily, and perform worse in their sport. Understanding which treatments actually work is important because it helps doctors and coaches make better decisions about how to help struggling athletes. By combining results from many studies, researchers can be more confident about what really works versus what might just seem to work by chance.

The researchers were honest about the limitations of their findings. Most of the studies they reviewed were rated as ’low to moderate quality,’ meaning they had some problems in how they were designed or conducted. The medicine studies were especially limited—only 4 studies tested medicine approaches, and they weren’t always well-designed. This means we should be confident about the lifestyle change findings but more cautious about the medicine findings. The researchers clearly stated that more and better studies are needed, especially for testing medicine approaches.

What the Results Show

Non-medicine approaches, especially nutrition interventions, showed clear benefits. When athletes received nutrition counseling and ate more calories, they gained an average of 1.36 kilograms of healthy body fat and improved their body fat percentage by 2.21%. These might sound like small numbers, but for athletes with energy deficiency, gaining healthy body fat is exactly what should happen and is a sign the treatment is working.

One of the most important findings was that lifestyle changes helped athletes get their menstrual periods back to normal. This matters because losing your period is one of the main signs that an athlete isn’t eating enough. When periods return, it usually means the body is getting the energy it needs again.

The research also looked at a hormone called T3 (triiodothyronine) that helps control metabolism. Non-medicine treatments showed changes in T3 levels, though the results were mixed. This suggests that eating more calories affects how the body’s metabolism works.

Medicine approaches showed some promise for improving bone mineral density (bone strength), which is important because athletes with energy deficiency often develop weak bones. However, only 4 studies tested medicine, so researchers can’t be very confident about these results yet.

Beyond the main findings, researchers noticed that different types of non-medicine treatments worked in different ways. Some athletes benefited most from nutrition counseling alone, while others improved more when counseling was combined with behavior changes and education about the condition. This suggests that a personalized approach might work better than a one-size-fits-all treatment. The research also showed that the longer athletes stayed in treatment programs, the better their results tended to be, suggesting that consistency matters.

This research builds on what doctors have suspected for years: that Relative Energy Deficiency in Sport is best treated by addressing the root cause (not eating enough) rather than just treating the symptoms. Previous smaller studies hinted at this, but this meta-analysis provides stronger evidence by combining results from many studies. The finding that lifestyle changes work better than medicine for most aspects of the condition aligns with how doctors now think about treating similar conditions in non-athletes. However, the finding about medicine potentially helping bone health is newer and needs more research to confirm.

The biggest limitation is that most studies were small and not perfectly designed. Researchers couldn’t always compare apples to apples because different studies measured different things in different ways. The medicine studies were especially limited—only 4 studies tested drugs, and they weren’t always well-controlled experiments. This means the findings about medicine are preliminary and shouldn’t be considered final. Additionally, almost all participants were female athletes, so we don’t know if these results apply to male athletes. Finally, most studies were relatively short-term, so we don’t know if the benefits last over many months or years.

The Bottom Line

If you’re an athlete with Relative Energy Deficiency in Sport: (1) Work with a sports nutritionist to increase your calorie intake—this is the most evidence-supported first step (HIGH CONFIDENCE). (2) Expect to see improvements in energy, menstrual function, and body composition within weeks to months of eating more (MODERATE CONFIDENCE). (3) Talk to your doctor about bone health screening, as this is an important concern (HIGH CONFIDENCE). (4) Consider medicine only if lifestyle changes alone aren’t working and your doctor recommends it, particularly for bone health concerns (LOW CONFIDENCE—more research needed).

This research is most relevant for female athletes in sports that emphasize leanness (like running, gymnastics, dance, or figure skating), coaches who work with these athletes, sports medicine doctors, and nutritionists. If you’re an athlete who has lost your period, feel constantly tired, or struggle with injuries, this research suggests you should talk to a doctor about whether you’re eating enough. Parents of young athletes should also pay attention, as energy deficiency can affect growing bodies. Male athletes should note that this research focused on females, so the findings may not directly apply to them, though the underlying principles likely do.

Realistic expectations: You might notice improved energy levels within 1-2 weeks of eating more calories. Menstrual periods typically return within 3-6 months of consistent improved nutrition. Body composition changes (gaining healthy fat) usually become noticeable within 4-8 weeks. Bone health improvements take longer—usually 6-12 months or more to see meaningful changes. These timelines vary based on how severe the deficiency was and how well you follow the nutrition plan.

Want to Apply This Research?

  • Track daily calorie intake and energy availability (calories consumed minus calories burned through exercise). Set a daily target based on your sport and training level, and log meals to ensure you’re meeting it. This creates accountability and helps you see patterns in your eating habits.
  • Use the app to set reminders for eating regular meals and snacks throughout the day, not just one or two large meals. Many athletes with energy deficiency skip meals or eat too little. Set notifications for breakfast, lunch, dinner, and 1-2 snacks to build consistent eating habits.
  • Track secondary markers monthly: menstrual cycle regularity (if applicable), energy levels during training (rate 1-10), and how you feel overall. Take progress photos monthly to visually see body composition changes. Share this data with your nutritionist or doctor during check-ins to adjust your nutrition plan if needed.

This research summary is for educational purposes only and should not replace professional medical advice. Relative Energy Deficiency in Sport is a serious medical condition that requires evaluation and treatment by qualified healthcare providers, including sports medicine doctors and registered dietitians. If you suspect you have an energy deficiency, please consult with your doctor before making any changes to your diet or training. The findings presented here are based on current research but represent an evolving field of study. Individual results may vary, and treatment should be personalized to your specific situation.