Researchers studied 483 active-duty Army soldiers to see if eating healthier foods would help them perform better in fitness tests. They found that soldiers who ate better-quality foods scored significantly higher on the Army Combat Fitness Test, which measures strength, power, and endurance. For every point increase on a healthy eating score, soldiers improved their fitness test scores by about 2 points. Soldiers who followed high-protein diets also performed better. This research suggests that what soldiers eat directly impacts how strong and fit they become, making nutrition just as important as exercise for military readiness.

The Quick Take

  • What they studied: Whether soldiers who eat healthier foods perform better on military fitness tests
  • Who participated: 483 active-duty Army soldiers and cadets from three Army bases, mostly men (87%), with an average age of 26 years old
  • Key finding: Soldiers with better eating habits scored about 30 points higher on fitness tests compared to those with poor eating habits. Each improvement in diet quality was linked to better fitness performance.
  • What it means for you: If you’re in the military or training hard, eating nutritious foods may help you build strength and endurance faster. This suggests diet quality matters as much as exercise for fitness goals, though individual results will vary based on many factors.

The Research Details

This was a cross-sectional study, which means researchers looked at a group of soldiers at one point in time rather than following them over months or years. The 483 soldiers completed a survey called the Military Eating Behavior Survey that asked about what they eat and how much they exercise. Researchers then compared their answers about diet quality to their actual fitness test scores from the Army Combat Fitness Test (ACFT), which includes six different exercises that measure strength, power, and endurance.

The researchers used a scoring system called the Healthy Eating Score-7 (HES-7) that rates how well someone follows healthy eating guidelines. The score ranges from 0 to 35, with higher scores meaning better eating habits. They also looked at whether soldiers followed specific eating styles, like high-protein diets or balanced diets.

The researchers used statistical analysis to determine if better eating habits were truly connected to better fitness performance, even after accounting for other factors that might affect fitness like age and activity level.

This study is important because it shows a real-world connection between diet quality and physical performance in actual military personnel. Rather than just studying nutrition in a lab, researchers looked at soldiers doing their real jobs and training. This helps military leaders understand that improving what soldiers eat could be a practical way to boost their fitness and readiness without requiring more training time.

This study has some strengths: it included a decent-sized group (483 soldiers), came from multiple Army bases, and used statistical methods to control for other factors. However, because it’s a cross-sectional study, it only shows a connection between diet and fitness at one moment in time—it doesn’t prove that eating better actually causes better fitness. The study also relied on soldiers reporting what they eat, which may not be completely accurate. The findings are most reliable for young, active military personnel and may not apply to other groups.

What the Results Show

The average fitness test score was 496 out of 600, and the average healthy eating score was 18 out of 35, showing that most soldiers had room to improve their diets. When researchers looked at the connection between diet and fitness, they found that each one-point increase in the healthy eating score was linked to a 2-point increase in fitness test performance. This relationship was very strong statistically (P < .001), meaning it’s very unlikely to be due to chance.

When comparing soldiers by diet quality groups, the differences were even more dramatic. Soldiers in the top group for healthy eating (scores of 23-34) performed about 30 points better on fitness tests than those in the lowest group (scores of 0-14). Even soldiers in the second-lowest diet quality group performed 19 points worse than the best eaters. These differences are meaningful because they represent real improvements in strength and endurance.

Soldiers who followed a high-protein eating style scored 16 points higher on fitness tests compared to soldiers who didn’t follow any specific eating pattern. Additionally, soldiers who ate either a balanced diet or high-protein diet had healthier eating scores that were 4 points higher than those without a specific eating approach.

The study found that specific eating patterns matter beyond just overall diet quality. High-protein eating styles showed the strongest connection to fitness performance. Soldiers who reported following a balanced diet or high-protein approach had better overall eating quality scores, suggesting these eating styles naturally lead to better nutrition choices. The consistency of these findings across different measurements suggests the connection between diet and fitness is real and not just due to chance.

Previous research has shown that diet quality is connected to fitness in elite athletes and general populations, but this is one of the first studies to specifically look at this relationship in military personnel using the newer Healthy Eating Score-7. The findings support what earlier research suggested—that what you eat directly impacts how your body performs during physical activity. This study adds to that knowledge by showing the relationship holds true in a military setting and with a quick, practical scoring system that military leaders could use.

This study has several important limitations. First, it only shows a connection between diet and fitness at one point in time, so we can’t say for certain that eating better actually causes better fitness—it could be that fit soldiers simply choose to eat better. Second, soldiers reported what they eat through a survey, which may not be completely accurate since people sometimes forget or misremember their eating habits. Third, the study included mostly men (87%) and young soldiers, so the findings may not apply equally to women or older adults. Finally, the study didn’t measure other important factors like sleep quality, stress levels, or genetics that could also affect fitness performance.

The Bottom Line

If you’re in the military or training for physical performance, focus on improving your diet quality by eating more whole foods, lean proteins, fruits, and vegetables. A high-protein eating style appears particularly beneficial for fitness performance. However, remember that diet is just one part of the equation—consistent exercise, adequate sleep, and proper training are equally important. These recommendations are supported by this research but should be combined with guidance from military nutritionists or your healthcare provider.

Active-duty military personnel, military cadets, and anyone training for physical performance should pay attention to these findings. The results are most relevant for young, healthy adults in military settings. If you have specific health conditions, dietary restrictions, or are taking medications, consult with a healthcare provider or military nutritionist before making major diet changes. These findings may also interest military leaders and trainers who want to improve soldier fitness and readiness.

You likely won’t see dramatic fitness improvements overnight. However, research suggests that consistent improvements in diet quality can lead to noticeable fitness gains within 4-8 weeks of training. The stronger your commitment to better eating habits, the more likely you’ll see improvements in strength, endurance, and overall fitness test performance. Remember that fitness improvements depend on combining good nutrition with consistent exercise and adequate recovery.

Want to Apply This Research?

  • Track your daily Healthy Eating Score-7 by logging the types of foods you eat each day, then compare weekly scores to your fitness test performance or workout results. Aim to increase your score by 1-2 points per week by adding more whole grains, lean proteins, fruits, and vegetables.
  • Set a specific goal like ’eat high-protein foods at 2 meals per day’ or ‘add 2 servings of vegetables to my daily meals.’ Use the app to log these specific foods and get immediate feedback on how they affect your healthy eating score. Track which eating patterns (high-protein, balanced diet, etc.) help you feel strongest during workouts.
  • Weekly: Compare your average healthy eating score to your workout performance metrics (strength gains, endurance improvements, fitness test scores). Monthly: Review trends to see if months with higher eating scores correlate with better fitness performance. Adjust your diet based on what patterns work best for your individual fitness goals.

This research shows a connection between diet quality and fitness performance in military personnel, but it does not prove that diet changes will guarantee fitness improvements for every individual. Results may vary based on genetics, training intensity, sleep, stress, and other health factors. Before making significant dietary changes, especially if you have health conditions, take medications, or have dietary restrictions, consult with a military nutritionist, registered dietitian, or your healthcare provider. This information is for educational purposes and should not replace professional medical or nutritional advice. Individual fitness and nutrition needs vary, and what works for military personnel may not apply equally to all populations.