IntroductionRecent studies have shown an increasing number of overweight and obese members serving in many armies. Overweight and obesity can be estimated using either body mass index or waist circumference measures. The aim of this research was to estimate the proportion of the Australian Army considered to be overweight and obese by waist circumference using the proxy measure of issued combat uniform waist size.MethodThe Australian Army has been progressively replacing combat uniforms with a new uniform design and camouflage pattern since 2016. The total number of issued combat uniforms by size was obtained from the points of issue for the three Australian Army combat brigades from the first issue of the new uniform in January 2016 through to November 2019. The waist size of issued combat pants was collated from each of the three points of issue, adjusted for measured waist size accuracy and sex, and analysed to estimate the proportion of overweight and obese soldiers in the Australian Army.ResultsThere were a total of 155 735 combat pants issued across the three points of issue. The mean waist size based on combat uniform pant size was found to be 90.4 cm, with an SD of 7.5 cm. Based on these data, approximately 23.3% of the Australian Army population can be estimated to be overweight and an additional 4.5% to be obese.ConclusionsThe Australian Army, like many western armies, has a significant proportion of overweight personnel. This can negatively affect operational capability, health and future healthcare costs both within the military and to society after military service has concluded. This is the first study to use a uniform waist size as a proxy to estimate overweight and obesity. This technique has application for the military, emergency services or any other organisation in which uniforms are provided.