Stress, well-being, and optimism in Portuguese youth: how do gender and age shape mental health and eating quality

Stress has been consistently linked to changes in eating behaviors and psychological well-being among adolescents and young adults, yet evidence remains fragmented regarding how gender, developmental stage, and psychological resources jointly shape these outcomes. Grounded in stress–coping models, self-regulation theories, and a life-span developmental perspective, this study examines age- and gender-related differences in stress, well-being, optimism, and eating quality within a post-lockdown context. A cross-sectional study was conducted with 951 Portuguese adolescents and young adults aged 15–26 years. Data were collected across three post-lockdown periods (2020–2022) and aggregated after confirming negligible time-related effects ( η 2 ≤ 0.010). Validated self-report measures assessed perceived stress, well-being, optimism, and eating quality. Main and interaction effects of gender and developmental stage were examined using ANOVA and MANOVA. Significant main effects of gender and age were found for stress, well-being, and optimism. Female participants reported higher stress and lower well-being and optimism than males, with small to moderate effect sizes ( η 2 ≈ 0.01–0.04). Young adults displayed lower stress and higher well-being and optimism than adolescents ( η 2 ≈ 0.02–0.05). Eating quality showed no significant gender differences and limited age variation. Interaction effects were modest. Higher optimism was consistently linked to more favorable well-being and eating profiles. Findings support an integrative model in which stress-related outcomes are shaped by gender, developmental stage, and psychological resources. Interventions should strengthen optimism, self-regulation, and stress management using developmentally tailored approaches.