Kaiqi Zhang ^*

• Ludong University, Yantai, China

This cross-sectional study explored the associations between dietary habits, physical activities, mental health, and body mass index (BMI) among young Chinese males and females aged 18 and 25 years. It also examined gender-specific differences in these associations. A total of 1528 young Chinese from various regions, including Shanghai, Guangdong, Beijing, Sichuan, Jiangsu, Shandong, Xinjiang, Henan, Zhejiang, Liaoning, Hubei, and Tibet, participated in the survey conducted from October 15, 2023, to February 25, 2024. Participants completed questionnaires on socioeconomic status, dietary habits, mental health, and physical activity levels. Dietary habits were assessed through a detailed questionnaire, physical activity levels were measured by gym hours and time spent on sports, and mental health was evaluated using the 7-item Generalized Anxiety Disorder scale. Participants were classified into four BMI categories - underweight, normal, overweight, and obese – using the standards of the International Obesity Task Force. Data were rationalized using Factor Analysis of Mixed Data and analyzed with Partial Proportional Odds and Generalized Ordered Logit Models. BMI served as the dependent variable, while dietary habits, physical activity and mental health were the independent variables. The study revealed that 24.8% of the participants were overweight and 6.8% were with obesity, with males being 2.9 times more likely to have obesity than females. A one-unit decrease in mental health was associated with a 0.08-0.12-unit increase in BMI, while each additional hour of physical activity per week was linked to a 0.2-0.4 unit decrease in BMI. Significant gender differences emerged: females perceived themselves as less active than males but placed higher importance on gym hours. Females also adhered more to healthy eating habits, such as not skipping breakfast and consuming five meals a day, while males were less concerned about their body image and weight gain. These findings underscored the critical role of dietary habits, physical activity, and mental health in understanding BMI variations among young Chinese adults.