BMI and Physical Activity, Military-Aged U.S. Population 2015-2020.

Introduction: Obesity and physical inactivity are considered possible U.S. national security threats because of their impact on military recruitment. The objectives of this study were to estimate the prevalence of (1) BMI eligibility for military entrance, (2) adequate physical activity participation among the BMI-eligible population, and (3) combined BMI eligibility and adequate physical activity.

Methods: This cross-sectional study of nonpregnant, military-aged civilians (aged 17-42 years) used objectively measured weight and height data and self-reported aerobic physical activity data from the 2015-2020 National Health and Nutrition Examination Survey. BMI eligibility was defined as 19.0-27.5 kg/m, per Department of Defense regulation. Adequate physical activity for entering initial military training was defined as ≥300 minutes/week of equivalent moderate-intensity aerobic physical activity from all domains, approximating U.S. Army guidance. Participants meeting both definitions were further classified as eligible and active. Analyses were conducted in 2021-2022.

Results: Of military-aged participants (unweighted n=5,964), 47.3% were eligible by BMI. Among BMI-eligible participants, 72.5% reported adequate physical activity. Taken together, 34.3% were both eligible and active. The prevalence of eligible and active status was higher among males, persons who were younger and non-Hispanic White, college graduates, and those with higher family income than among their counterparts.

Conclusions: Among the military-aged U.S. population, slightly under half were eligible to enter the military on the basis of their BMI, and only 1 in 3 met BMI eligibility and were adequately physically active. Equitable promotion of healthy weight achievement and physical activity participation may improve military preparedness.