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 USA: challenges for military recruitment. Specifically, this paper estimates the percentage of the US military-age population that exceeds the US Army's current active duty enlistment standards for weight-for-height and percent body fat, 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 more than doubled for men and tripled for women during that time. As of 2007–2008, 5.7 million men and 16.5 million women exceeded the Army's enlistment standards for weight and body fat. We document disparities across race and education in exceeding the standards and estimate that a further rise of just 1% in weight and body fat would further reduce eligibility for military service by over 850 000 men and 1.3 million women. The paper concludes with a discussion of the implications of these findings for military recruitment and defense policy. Copyright © 2011 John Wiley & Sons, Ltd.