(Photo: Military Times. Jacob Sippel/Naval Hospital Jacksonville. 13 May 2019)
Introduction
For military veterans and first responders, maintaining physical fitness is a key component of job performance and long-term health. However, one common mistake is placing too much emphasis on weight rather than body composition—the balance of fat, muscle, bone, and water in the body. Body composition is a far more accurate measure of health, particularly when considering its impact on chronic inflammation, immune function, and disease risk.
This article explores why body composition matters more than weight, how excess fat mass contributes to inflammation and disease, how the immune system is affected by poor body composition, and practical ways to assess and improve body composition.
Why Body Composition Matters More Than Weight
Many people rely on Body Mass Index (BMI) to assess health, but this can be misleading. BMI does not differentiate between fat and muscle mass, meaning a muscular individual could be classified as overweight or obese despite being in excellent health. More importantly, excess body fat, particularly visceral fat, is a strong predictor of metabolic disease, independent of total body weight (Gitsi et al., 2024; Wang et al., 2024).
Studies show that fat-free mass (muscle) is the primary determinant of resting metabolic rate (RMR), meaning individuals with higher muscle mass burn more calories at rest (Zampino et al., 2020; Zurlo et al., 1990). This helps regulate energy balance and prevents excess fat accumulation. In contrast, individuals with higher fat mass tend to have a lower RMR and are at increased risk for obesity-related diseases.
Body Composition and Chronic Inflammation
Excess body fat, particularly visceral fat, is metabolically active and secretes pro-inflammatory cytokines, leading to a state of chronic low-grade inflammation known as meta-inflammation (Gleeson et al., 2020; Drucker, 2021). This persistent inflammatory state has been linked to insulin resistance, cardiovascular disease, and metabolic dysfunction.
A study by Katare et al. (2022) found that obese individuals exhibit metabolic inflexibility, meaning their muscles have a reduced capacity to burn fat efficiently, contributing to increased inflammation and metabolic dysfunction. Furthermore, higher body fat percentages correlate with increased circulating inflammatory markers, further exacerbating disease risk (He et al., 2021).
How Chronic Inflammation Contributes to Disease
Chronic inflammation driven by poor body composition plays a direct role in the development of several conditions, including:
- Cardiovascular disease: Inflammation promotes arterial plaque buildup, increasing the risk of heart attacks and strokes (Wang et al., 2024).
- Type 2 diabetes: Chronic inflammation disrupts insulin signaling, leading to insulin resistance and hyperglycemia (Pantanetti et al., 2024).
- Cancer: Pro-inflammatory cytokines promote tumor growth and increase cancer risk (Chen et al., 2024).
- Autoimmune disorders: Prolonged immune activation can trigger self-reactive immune responses, increasing susceptibility to autoimmune diseases (He et al., 2021).
An Exhausted Immune System and Disease Susceptibility
When the immune system is constantly battling inflammation caused by excess body fat, it becomes less effective at responding to actual threats, such as infections. This was highlighted during the COVID-19 pandemic, where obesity significantly increased the risk of severe disease and hospitalization (Rippe & Foreyt, 2021).
Several studies found that individuals with obesity had dysregulated immune responses to viral infections, leading to more severe outcomes (Gleeson et al., 2020; Drucker, 2021). Additionally, obesity has been linked to lower vaccine efficacy, meaning overweight individuals may have weaker immune protection against infections (Sheedy et al., 2020).
(Photo: Marine Corps Times. Lance Cpl. George Nudo/Marine Corps, 22 August 2022)
Top Three Measures for Assessing Body Composition
- Dual-Energy X-ray Absorptiometry (DXA) – A gold standard method for measuring fat, muscle, and bone density.
- Bioelectrical Impedance Analysis (BIA) – A practical, widely available tool that estimates fat and muscle mass using electrical currents (Pantanetti et al., 2024).
- Waist-to-Hip Ratio (WHR) – A simple measure that predicts disease risk based on fat distribution, with higher ratios indicating greater visceral fat accumulation (Gitsi et al., 2024).
How to Improve Body Composition
Improving body composition involves reducing fat mass while preserving or increasing muscle mass. Key strategies include:
- Strength Training: Resistance exercises like weightlifting stimulate muscle growth and increase resting metabolic rate (Zampino et al., 2020).
- Aerobic Exercise: Activities such as running, cycling, and swimming help burn excess fat and improve cardiovascular health (Wang et al., 2024).
- Nutrient-Dense Diet: Prioritizing protein intake while minimizing processed foods supports muscle maintenance and fat loss (Pantanetti et al., 2024).
- Adequate Sleep: Sleep deprivation disrupts hormone regulation and promotes fat accumulation (Drucker, 2021).
- Stress Management: Chronic stress increases cortisol levels, leading to increased fat storage, particularly in the abdominal region (Gleeson et al., 2020).
Why This Matters for Veterans and First Responders
For veterans and first responders, physical resilience and disease prevention are critical for long-term health and performance. Poor body composition not only increases the risk of chronic disease but also impairs recovery from injuries, reduces mobility, and weakens immune function. Given the physically demanding nature of their careers, maintaining an optimal body composition is essential for operational readiness and post-service health.
Summary
- Body composition is more important than weight for assessing health.
- Excess body fat contributes to chronic inflammation, leading to metabolic diseases.
- Chronic inflammation weakens the immune system, making individuals more susceptible to infections and autoimmune disorders.
- Obesity worsened COVID-19 outcomes, highlighting the importance of maintaining a healthy body composition.
- DXA, BIA, and WHR are effective tools for measuring body composition.
- Resistance training, aerobic exercise, proper nutrition, sleep, and stress management are essential for improving body composition.
Key Takeaways
- Veterans and first responders should focus on body composition rather than weight.
- Reducing visceral fat and increasing muscle mass lowers inflammation and disease risk.
- A strong immune system starts with a healthy body composition.
- Simple lifestyle changes can dramatically improve long-term health and performance.
References
Chen, B., Wang, Y., & Ma, D. (2024). The role of nutrition and body composition on metabolism. Nutrients, 16(1457). https://doi.org/10.3390/nu16101457
Drucker, D. J. (2021). Diabetes, obesity, metabolism, and SARS-CoV-2 infection: The end of the beginning. Cell Metabolism, 33(3), 479–498. https://doi.org/10.1016/j.cmet.2021.01.016
Gitsi, E., Kokkinos, A., Konstantinidou, S. K., Livadas, S., & Argyrakopoulou, G. (2024). The relationship between resting metabolic rate and body composition in people living with overweight and obesity. Journal of Clinical Medicine, 13(5862). https://doi.org/10.3390/jcm13195862
Gleeson, L. E., Roche, H. M., & Sheedy, F. J. (2020). Obesity, COVID-19, and innate immunometabolism. British Journal of Nutrition. https://doi.org/10.1017/S0007114520003529
He, S., Le, N., Ramirez-Zea, M., Martorell, R., Narayan, K. M. V., & Stein, A. D. (2021). Metabolic flexibility differs by body composition in adults. Clinical Nutrition ESPEN, 46, 372–379. https://doi.org/10.1016/j.clnesp.2021.09.730
Katare, P. B., Dalmao-Fernandez, A., Mengeste, A. M., Hamarsland, H., Ellefsen, S., Bakke, H. G., Kase, E. T., Thoresen, G. H., & Rustan, A. C. (2022). Energy metabolism in skeletal muscle cells from donors with different body mass index. Frontiers in Physiology, 13, 982842. https://doi.org/10.3389/fphys.2022.982842
Pantanetti, P., Cangelosi, G., Alberti, S., Di Marco, S., Michetti, G., Cerasoli, G., Di Giacinti, M., Coacci, S., Francucci, N., Petrelli, F., Ambrosio, G., & Grinta, R. (2024). Changes in body weight and composition, metabolic parameters, and quality of life in patients with type 2 diabetes treated with subcutaneous semaglutide in real-world clinical practice. Frontiers in Endocrinology, 15, 1394506. https://doi.org/10.3389/fendo.2024.1394506
Rippe, J., & Foreyt, J. P. (2021). COVID-19 and obesity: A pandemic wrapped in an epidemic. American Journal of Lifestyle Medicine. https://doi.org/10.1177/1559827621995393
Sheedy, F. J., Gleeson, L. E., & Roche, H. M. (2020). Obesity, COVID-19, and innate immune dysfunction. British Journal of Nutrition. https://doi.org/10.1017/S0007114520003529
Wang, Y., Chen, B., & Ma, D. (2024). The role of nutrition and body composition on metabolism. Nutrients, 16(1457). https://doi.org/10.3390/nu16101457
Zampino, R., Marrone, A., Restivo, L., Mele, F., Vitale, C., Durante-Mangoni, E., & Nevola, R. (2020). The impact of body composition on metabolic health and inflammation. Frontiers in Immunology. https://doi.org/10.3389/fimmu.2020.01845
Zurlo, F., Larson, K., Bogardus, C., & Ravussin, E. (1990). Skeletal muscle metabolism is a major determinant of resting energy expenditure. Journal of Clinical Investigation, 86(11), 1423–1427. https://doi.org/10.1172/JCI114857
