BACKGROUND: COVID-19 lockdown measures have profoundly altered lifestyle habits, exposing individuals to significant health risks Aim: This study aims to assess the impact of quarantine measures in Tunisia, with a focus on examining changes in dietary habits, levels of physical activity, psychological patterns, and factors contributing to weight gain. METHODS: This is a cross-sectional study involving 1,016 participants and employed a mixed-methods approach to gather data on dietary habits, physical activity levels, and psychological indicators. Statistical analyses, including binary logistic regression, were conducted to identify independent risk factors associated with weight gain during the quarantine period. RESULTS: Approximately 36.4% of participants reported experiencing weight gain, with a notable prevalence among younger age groups. Increased consumption of sweets, pasta, and fried foods, coupled with reduced intake of water, vegetables, and fruits, were associated with weight gain. Furthermore, a decline in physical activity levels and elevated scores of anxiety and depression were observed among individuals who reported weight gain. Binary logistic regression highlighted snack frequency, fried food consumption, and pasta intake as significant independent risk factors for weight gain. CONCLUSION: The results underscore the importance of understanding the complex impacts of lockdowns on lifestyle habits and mental health to guide future interventions, which are necessary to mitigate adverse health consequences and promote healthy lifestyles in the post-pandemic period.