Background: National Health and Nutrition Examination Survey data from the 1960s to 2010s confirm that pediatric obesity rates are increasing. To assess obesity in the Military Health System (MHS), we evaluated a pediatric cohort's trends in BMI categorization from 2009 to 2016. Methods: We identified two age-based pediatric cohorts in the United States using the MHS Data Repository. We tracked them for BMI from 2009 to 2016. We calculated BMI percentiles and z-scores using validated growth charts, and biologically implausible BMI z-scores were removed from analyses. Using the Stuart-Maxwell test, we assessed the percent change in BMI categorization from 2009 to 2016 and stratified by age group. Results: Our cohort consisted of 130,675 pediatric patients (52.2% males and 47.8% females). The proportion in each BMI categorization changed significantly from 2009 to 2016 in all groups (p < 0.001). Increases in the Overweight and Moderate or Severe Obesity categories were observed in all age groups (2-5, 6-10, and 2-10), and increases in Obese were observed in 6-10-year olds. Most shifts occurred from healthy-weight individuals increasing in BMI category. Conclusions: We observed a significant increase in the proportion of children with overweight and obesity in a nationally representative MHS cohort from 2009 to 2016. The prevalence of obesity, but not overweight, in our cohort mirrored the civilian population. Increasingly heavier MHS and civilian children have implications for our future military force, as they are ineligible for military service if unable to meet weight standards.
Keywords: Military Health System; child welfare; national security; pediatric health; pediatric overweight.