The Importance of Physical Activity and Eating Behaviours for Fat and Muscle Mass in Young Men and Women

Purpose: The aim of the study was to determine the relationships between the level of physical activity and eating-related behaviors (such as emotional eating, habitual eating, and dietary restraint) and the amount of fat and muscle tissue in the bodies of young adults. Methods: The study was conducted among 202 university students (103 women - age 21.44 ±2.14 years, stature 167.91 ±6.13 cm, body mass 62.08 ±12.11 kg; 99 men - age 21.48 ±1.93 years, stature 179.12±7.11 cm, body mass 77.31±15.32 kg) from two higher education institutions. Self-report questionnaires were used: the IPAQ (International Physical Activity Questionnaire) and the KZZJ (Eating Behavior Questionnaire). Anthropometric measurements and body composition analyses were also performed. Data were analyzed using Pearson's r correlations, Mann–Whitney U tests, Pearson's χ² tests, and structural equation modeling (SEM). Results: Strong positive correlations were observed between emotional eating and the level of body fat. It was found that only individuals with high-intensity physical activity (over 1500 MET-min/week) had body fat levels within the normal range. For smaller adipose tissue, only the following correlations were statistically significant: intensive exercise around the house (R=- .143, P= .043), intensive physical activity in free time (R= -.268, P< .001) and moderate physical activity in free time (R= - .188, P= .008). For larger muscle tissue, the following correlations were statistically significant: intensive exercise around the house (R=. 140, P= .048), intensive physical activity in free time (R= .198, P= .005). SEM models showed that psychological and physical activity-related variables explained 48% of the variance in body fat and 32% of the variance in muscle mass. Conclusions: Physical activity, especially at a high intensity, plays a crucial role in maintaining a healthy body composition. At the same time, emotional eating contributes to increased body fat, particularly in women. The findings have practical applications for the prevention of overweight, obesity, and eating disorders among young adults.