The objectives of this prospective study were to explore the health-related lifestyle of police cadets and assess changes in their health behaviors following entry into the police force. To do so, 190 police cadets completed an online questionnaire assessing their physical activity level, sedentary behaviors, diet quality, sleep hygiene, alcohol consumption, cigarette smoking, and stress level. One year following their graduation from the police training program, participants were invited to, once again, complete the questionnaire. Our results suggest that police cadets generally display healthy lifestyles, with very few cadets being physically inactive, smokers, reporting insufficient sleep duration, and displaying obesity. Nevertheless, paired-sample comparisons highlighted significant decreases in physical activity, fruit and vegetable intake, sleep duration, and sleep quality at the follow-up. Likewise, significant increases in fast-food consumption and BMI were observed.