Obesity is a growing global concern, with significant implications for both civilian and military populations. The World Health Organization (WHO) reported that in 2014, 39% of adults aged 18 years or older were overweight, with 1.9 billion adults classified as overweight and 600 million as obese. Projections suggest that by 2025, this number will reach 2.7 billion. This trend also affects the military, impacting recruitment and the maintenance of military personnel. In the U.S. military, overweight and obesity prevalence among active-duty soldiers was 49.3% and 19.4%, respectively, in 2012. Physical fitness, weight, and body composition standards are crucial in military occupations, ensuring personnel can meet the physical demands of their roles and reduce injury risks. However, military personnel face challenges such as access to unhealthy, energy-dense foods, especially during deployment and relocation, increasing their risk of weight gain.
Factors Contributing to Weight Gain in Military Personnel
Several factors contribute to obesity within the military population. Studies have indicated that obesity is more prevalent among men, individuals over 35 years of age, those with lower ranks, and married officers. Certain ethnic groups, such as African-American and Hispanic individuals, also show a higher prevalence. Overweight and obesity can lead to reduced quality of life, decreased work productivity, and joint and back disorders, in addition to common consequences like type 2 diabetes and hypertension. Obesity also has a significant economic impact in the military setting. Addressing obesity requires a comprehensive approach that includes nutrition education, programs, and environmental changes, such as policies and modifications to workplace food environments. Interventions based on theories like self-regulation have shown potential effectiveness.
Guidelines and Approaches for Weight Management
The Veterans Affairs (VA) and Department of Defense (DoD) have established clinical guidelines for primary care clinicians to screen and treat overweight and obesity among military personnel. These guidelines emphasize a comprehensive, interdisciplinary approach that combines dietary adjustments, physical activity, and behavioral components. Lifestyle interventions that offer a more structured and advanced approach to treating and preventing obesity are more effective than standard physical training in the military.
Systematic Review of Military Weight Management Interventions
To assess the effectiveness of weight management, dietary, and physical activity interventions in military settings, a systematic review was conducted. The review aimed to evaluate the impact of these interventions on dietary behaviors, fitness levels, and body composition measures like BMI and body fat percentage among active-duty military personnel.
Methodology
The systematic review followed PRISMA guidelines. Electronic searches were conducted on November 17, 2017, using PubMed, PsycInfo, and CINAHL databases. Specific search terms were used to identify relevant studies related to interventions, outcome measurements, and the military population. Studies were included if they focused on active-duty military personnel and assessed outcomes related to anthropometric measurements, dietary behaviors, or fitness/physical activity levels. Studies targeting veterans, military family members, or retired military personnel were excluded.
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Study Selection
The initial search identified 9319 citations. After removing duplicates, 7156 articles were screened by title, followed by abstract and full-text assessments. Two reviewers independently screened the citations, resolving disagreements through discussion. A total of 136 studies were selected for the final review. These studies were divided into two categories: educational and behavioral change interventions, and basic military training interventions without additional educational or behavioral components. Given the review's focus on weight management and behavioral change, data extraction and quality assessment were restricted to the educational and behavioral change interventions.
Data Extraction and Quality Assessment
A standardized data extraction form was used to collect data on study design, participant characteristics, intervention details, outcome measurements, and results. Intervention effectiveness was determined by significant changes (p < 0.05) in body weight, BMI, anthropometric measures, dietary intake, or fitness-related measures. The quality of the educational and behavioral change intervention studies was assessed using the Effective Public Health Practice Project (EPHPP) tool, which evaluates selection bias, study design, confounders, blinding, data collection methods, and withdrawals/dropouts.
Characteristics of Included Studies
The qualitative synthesis included 38 studies. Most studies were conducted in the U.S., followed by Europe. Some studies included recruits during basic military training, while others focused on fully qualified military personnel. The studies were conducted across different military branches, including the Navy, Air Force, and Army. The study designs included RCTs, nonrandomized control trials, longitudinal studies, and retrospective studies. Sample sizes ranged from 18 to 68,591 participants, with study durations ranging from six weeks to five years.
Quality Assessment Results
The quality assessment revealed that 28 studies received a weak rating, eight received a moderate rating, and two received a strong rating. The primary reason for weak ratings was selection bias, often due to unreported recruitment methods or non-representative target populations.
Findings and Outcomes of Interventions
The review found good evidence that military weight management interventions are effective in improving body composition for up to 12 months. Effective interventions are typically high intensity, delivered by specialists, and incorporate theoretical bases, behavioral change techniques, and standardized guidelines. Dietary interventions can potentially reduce total fat and saturated fat intake, with interventions targeting kitchen staff or increasing the availability of healthy food showing more effectiveness in the short term.
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Exercise-Only Interventions
Studies that focused solely on exercise reported minor effects, such as a reduction in weight (-0.5 kg), BMI (-0.3 kg/m²), waist circumference (-0.1 cm), and body fat percentage (-1.1%), without significant effect sizes.
Nutritional Programs
Nutritional programs alone reported low to moderate effect sizes.
Combined Programs
Combined programs that included both dietary and exercise countermeasures were more effective than programs based solely on diet or exercise. Programs combining exercise and educational methods showed moderate to large effect sizes (ES 0.6-1.3) for weight reduction.
Pharmacological Treatments
Pharmacological treatments for reducing fat intake resulted in larger effect sizes for weight loss.
Key Components of Effective Interventions
Effective countermeasures for reducing body weight included combined interventions such as education on lifestyle changes, dietary habits, and the promotion of physical activity in military personnel. Ketogenic dietary interventions combined with physical activity, followed by pharmacological intervention approaches, also proved effective.
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Specific Intervention Examples
Several studies provided specific examples of effective interventions:
- Intensive Training Programs: An intensive endurance and strength training intervention over 6 to 12 months in Finnish military personnel showed significant improvements in body composition and cardiovascular disease risk factors.
- Dietary Interventions: A twelve-week dietary intervention comparing low-carb and low-fat diets demonstrated that a low-carb diet led to a weight loss of -5.5 kg and a reduced waist circumference of -4.8 cm, while a low-fat diet resulted in a decrease of -2.0 kg and -3.3 cm.
- Synbiotic Supplementation: A double-blinded, placebo-controlled trial using a synbiotic nutritional supplement in military personnel with metabolic syndrome resulted in significant reductions in BMI and waist circumference in the experimental group.
- Meal Replacement Programs: The US Army ‘Weigh to Stay’ program, which included meal replacements, resulted in weight loss and reduced fat mass, although there were no statistically significant differences compared to the ‘Weigh to Stay’ program alone.
- mHealth Approaches: While wearable technologies showed promise in promoting physical activity, they were not effective in preventing weight regain in the long term.
- Ketogenic Diets: A combined exercise and dietary intervention using a ketogenic diet resulted in significant weight loss, body fat percentage reduction, and visceral fat loss compared to a mixed diet.
- Lifestyle Interventions: A single 4-hour lifestyle intervention (“Be Well” Course) for US Air Force members who failed to meet fitness assessments resulted in improvements in fitness test scores and decreases in BMI and waist circumference.
- Internet-Based Programs: An internet-based behavioral treatment for weight-gain prevention showed small but positive effects on weight loss, BMI reduction, and waist circumference reduction.
Comprehensive Weight Management Programs
Comprehensive weight management programs like "Fit For Performance" focus on a combination of diet and exercise modifications, as well as sleep and mindfulness, to improve weight loss success. These programs emphasize energy balance, obesity risks, BMI, body composition, goal setting, and making small changes over time.
Challenges and Considerations
Despite the effectiveness of various interventions, military personnel and their families face unique challenges that influence their ability to manage their weight. These challenges include permanent changes of station, moves, training requirements, and deployments, which are less common in the civilian population. Quick weight-loss programs can often be expensive and frustrating, with no real long-term benefits.