This study examined whether overweight or obesity results in greater discharge risk from basic military training (BMT) or during the first year of service in the U.S. Air Force (USAF). Participants were 32,144 male and female airmen who underwent BMT from August 1995 to August 1996 and were classified as underweight (body mass index [BMI] < 18), normal range (BMI = 18-24.9), overweight (BMI = 25-29.9), or obese (BMI ≥ 30). Underweight airmen were 63% more likely and overweight airmen were 24% more likely to be medically discharged during BMT compared with individuals in the normal range. Underweight airmen were 22% more likely to be discharged within the first year of service compared with those in the normal range, whereas overweight airmen were 15% less likely to be discharged. These findings do not support overweight or obesity as being major causes for discharge from the USAF within the first year of active duty.