This paper contributes to the literature on the labor market consequences of unhealthy behaviors and poor health by examining a previously underappreciated consequence of the rise in obesity in the United States: challenges for military recruitment. Specifically, this paper estimates the percent of the U.S. military-age population that meets, and does not meet, current active duty enlistment standards for weight-for-height and percent body fat for the U.S. Army, using data from the series of National Health and Nutrition Examination Surveys that spans 1959-2008. We calculate that the percentage of military-age adults ineligible for enlistment because they are overweight and overfat doubled for men and tripled for women during that time. We document disparities across race, education, and age in meeting the standards, and finds that a further rise of just 1% in weight and body fat would further reduce eligibility for military service by over 600,000 men and 1 million women of military age. The paper concludes with a discussion of the implications for military recruitment and military policy.