Objectives: The aim of this paper was to investigate the impact of changes in the students’ lifestyle during an examination period on their health condition, as evidenced by changes to the body composition and metabolic rates. Material and Methods: The study involved 268 Wroclaw Medical University students (second- and third-year students). The study was performed 3 times (at the beginning of a semester, in the middle of a semester, and in the examination period) and included a completion of a questionnaire on the current lifestyle, as well as measurements of the body composition, the basal metabolic rate, and the waist and hip circumferences. The measurements were carried out with the use of a body composition analyzer (Tanita MC-780 MA) and a tape measure with a waist–hip ratio calculator. Results: In the examination period, as compared with the rest of the semester, a significant decrease was observed in the metabolic rates, and the body water and muscle mass of the examined students. During that period, there were also more frequent adverse changes in the students’ lifestyle. In the studied periods, a correlation was found between changes in the frequency of snacking, consuming sweets and cola drinks, and the alterations of the subjects’ body fat mass, i.e., r = 0.161, r = 0.135, and r = 0.143, respectively. In turn, differences in the frequency of drinking wine, physical activity, sleep length, and time devoted to learning correlated with changes in the participants’ body water, i.e., r = 0.140, r = 0.152, and r = 0.133 (r = −0.142, r = −0.147), respectively, and muscle mass, i.e., r = 0.141, r = 0.142, and r = 0.126 (r = −0.130, r = −0.142), respectively, and metabolism, i.e., r = 0.127, r = 0.145 and r = 0.135 (r = −0.127, r = −0.135), respectively. Conclusions: The analysis of the body composition and metabolic rates of the students during an examination period indicates that the changes occurring in various elements of their lifestyle (e.g., dietary habits, physical activity) can result in deteriorating their health condition. Int J Occup Med Environ Health. 2020;33(3):339–51