Body Mass Index, Medical Qualification Status, and Discharge during the First Year of U.S. Army Service

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. In this study, we examined the effect of body mass index (BMI; in kg/m(2)) and medical status on premature discharge from the US Army in a large cohort of first-time-enlisted, active-duty soldiers. 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. 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). 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.