Abstract: Background and Aim: Obesity is influenced by genetic, behavioral, and nutritional factors and has many negative effects on physical and mental health. Therefore, this study aimed to investigate the relationship between obesity, sleep quality, sleep quantity, and insomnia in military personnel. Methods: The current study was a cross-sectional study conducted among the armed forces. Demographic information (gender, age, education level, marital status) was evaluated through observation and interviews. Anthropometric indices such as height, weight, and body mass index (BMI) were also measured. The Pittsburgh Sleep Quality Index, Insomnia Severity Index, and Epworth Sleepiness Scale questionnaires were used to evaluate sleep quality, insomnia severity, and sleep quantity, respectively. Multiple regression analysis was employed to evaluate the data. Results: According to the results of the present study, the average body mass index (BMI) among the staff was 26.47, with 23.8% classified as obese. Only 27.3% of the participants had adequate sleep quality; however, in terms of sleepiness, more than half of the participants (53.8%) were in a normal state. The results indicated an inverse relationship between obesity and sleep quantity (r = 0.121, P = 0.041) and sleep quality (r = 0.163, P = 0.006). Additionally, a direct relationship between obesity and insomnia (r = 0.116, P = 0.039) was observed. Conclusion: The findings of this study suggest that the majority of military personnel do not have good sleep quality, and that poor sleep quality and quantity may increase the incidence of obesity.