A cohort study of body mass index changes among U.S. Air Force personnel during the COVID-19 pandemic

Background: The impact of the COVID-19 pandemic period continues to be felt, including a resulting increase in prevalence and rates of individuals with obesity within the Unites States, which had already been trending upward prior to the pandemic. This study aims to identify changes in body mass index (BMI) among the active-duty U.S. Air Force (USAF) personnel prior to and during the pandemic. Materials and Methods: We conducted a retrospective cohort study of USAF active-duty personnel. BMI data points were sourced from the Military Health System Data Repository and included a measure from each period: pre- (September 1, 2018 – February 28, 2020), early (March 1, 2020 – September 30, 2020), and late pandemic (October 1, 2020 – September 30, 2022). Pregnant women delivering during or one year prior to the study periods were excluded. Statistical analysis included percent change, the Stuart-Maxwell test for marginal homogeneity, and ANOVA comparing mean BMI with post-hoc mean comparisons. Additionally, the percentage change toward obese BMI was stratified by rank and occupation. Results: We identified a cohort of 111,392 active-duty USAF personnel. The overall increase in prevalence of USAF personnel with obesity over the entire study period was 44.1%. The prevalence of USAF personnel with obesity among our cohort increased by 11.6% from the pre-pandemic period to the early pandemic period (18% pre-pandemic; 20.8% early pandemic) with a 29.1% increase in prevalence from the early to late pandemic periods (20.8% early pandemic; 26.9% late pandemic). USAF aircrew members progressed to having a BMI of obese at lower rates over the same periods increasing by 7.8%, 21.3%, and 30.7%, respectively. The most prominent changes were observed among females, personnel between the ages 20 and 24, of American Indian or Alaska Native race, and in junior enlisted ranks. Conclusions: Our analysis indicates that like the other service branches of the U.S. military, the Air Force experienced an increase in active-duty personnel with obesity during the COVID-19 pandemic period. This indicates increases in rates of service members with obesity across the U.S. armed forces, which is likely to result in decreased force readiness.