Body mass index, medical qualification status, and discharge during the first year of US Army service

Background: The high prevalence of overweight and obesity in military recruits and in the US population as a whole necessitates understanding the health effects of body composition and associated morbidity. Objective: In this study, we examined the effect of body mass index (BMI; in kg/m²) and medical status on premature discharge from the US Army in a large cohort of first-time-enlisted, active-duty soldiers. Design: We determined the odds ratios (ORs) associated with BMI and medical status at enlistment by using a retrospective cohort of first-time, active-duty army recruits. Results: ORs for BMI, calculated by using 24-24.9 as a reference, exhibited a U-shaped pattern. Soldiers with a BMI >34 had the highest ORs for all-cause (OR: 1.47; 95% CI: 1.32, 1.64) and medical (OR: 1.68; 95% CI: 1.46, 1.93) discharges. A BMI <17 was 1.35 times as likely (95% CI: 1.02, 1.80) to result in an all-cause discharge and 1.45 times as likely (95% CI: 1.01, 2.08) to result in a medical discharge. ORs for soldiers who required a medical reexamination did not vary when all-cause discharge (OR: 1.10; 95% CI: 1.06, 1.14) and medical discharge (OR: 1.10; 95% CI: 1.05, 1.15) were compared. The medical discharge OR for soldiers who required a medical waiver to enter the army (OR: 1.56; 95% CI: 1.48, 1.64) was higher than the OR for all-cause discharge (OR: 1.27; 95% CI: 1.22, 1.32). Conclusion: Enlistment BMI and medical qualification status play an important role in early discharge and may provide a valuable tool in the development of fitness, nutrition, and injury-prevention interventions in higher-risk groups.