Impact of Exams on Diet, Physical Activity, and Body Composition in University Students

Abstract

Background: Bad dietary habits and sedentary lifestyles alter body composition, increasing disease risk.

Methods: We conducted a prospective, comparative, longitudinal observational study among nursing students from Complutense University of Madrid. Data were collected in two periods: before exams (January 2024) and during exams (May 2024). Body composition was assessed via bioimpedance (Beurer BF 1000), dietary habits through the modified Kidmed survey, and physical activity using the IPAQ.

Results: During exam preparation, fat mass significantly increased (25.43% to 28.79%, p = 0.016), muscle mass significantly decreased (39.70% to 36.20%, p < 0.001), and visceral fat rose notably (2.34 to 3.52, p < 0.001). Students exhibiting poor dietary quality increased (54.2% to 80.0%, p < 0.001), vigorous physical activity dramatically decreased (84.7% to 11.1%, p < 0.001), and sedentary time increased significantly (408.24 to 543.61 min/day, p < 0.001).

Conclusions: Our findings suggest dietary deterioration and reduced physical activity during exams adversely affect students' body composition.

Keywords: bioimpedance; body composition; dietary habits; exams; physical activity; stress; students; university students.

Figure 1

Flowchart of the study design. The study involved 142 second-year nursing students who underwent two assessments: one before the exam period (January 2024) and another during the exam period (May 2024). Each assessment included measurements of body composition (via bioimpedance), dietary habits (Kidmed questionnaire), and physical activity levels (IPAQ-SF).

Figure 2

This figure illustrates individual trajectories in fat mass for a random subset of 10 participants, for visualization purposes. Violin and box plot of fat mass distribution before and during exams, including individual trajectories for a subset of 10 students. The figure highlights both the shift in distribution and the within-subject variability associated with academic stress.

Figure 3

Stacked bar chart showing the distribution of Mediterranean diet quality among students before and during the exam period. The figure illustrates a marked decline in diet quality during exams, with a substantial increase in the number of students classified as having low adherence to the Mediterranean diet.

Figure 4

Total weekly minutes of vigorous physical activity, sedentary time, and walking before and during the exam period. The figure illustrates a significant decline in physical activity and walking, alongside a marked increase in sedentary behavior during exams. Data are based on calculated totals from self-reported frequency and duration.

Figure 5

Distribution of fat mass and muscle mass according to diet quality. The boxplots illustrate that students with lower diet quality (as classified by the modified Kidmed score) tend to have higher fat mass and lower muscle mass, reinforcing the association between nutritional habits and body composition.

Figure 6

Correlation matrix of key variables related to lifestyle and body composition. The heatmap displays Pearson correlation coefficients between the Kidmed score, IPAQ physical activity score (MET-min/week), fat mass, muscle mass, visceral fat, and sedentary time. Strong inverse correlations are observed between Kidmed and IPAQ scores and fat-related measures, highlighting the impact of healthy habits on body composition.

Figure 7

Conceptual summary of the impact of exam periods on student health. The infographic illustrates how academic stress leads to unhealthy habits, including poor diet and physical inactivity, which subsequently result in increased fat mass and decreased muscle mass, reflecting adverse changes in body composition.