Complex associations among weight selfstigma, depression, and treatment acceptance self-efficacy in Japan

Weight-related self-stigma has been recognized as an important psychosocial factor associated with obesity, depression, and reduced healthcare engagement. However, its characteristics and clinical implications in Japan remain insufficiently understood. This study aimed to examine the relationships among body mass index (BMI), weight self-stigma, depressive symptoms, and treatment acceptance in a Japanese population. A cross-sectional web-based survey was conducted among 309 Japanese adults recruited through a commercial survey panel. Participants completed the Japanese versions of the Weight Self-Stigma Questionnaire (WSSQ-J), Patient Health Questionnaire-9, and Self-Efficacy Scale for Treatment Acceptance (SESTA). Participants were classified into three BMI groups: Low BMI (<18.5 kg/m2, n = 32), Middle BMI (18.5–24.9 kg/m2, n = 223), and High BMI (>25.0 kg/m2, n = 54). The mean BMI of the sample was 22.3 kg/m2, which falls within the normal range according to international criteria. Nevertheless, participants reported relatively high levels of weight self-stigma, with mean WSSQ scores comparable to those observed among patients with obesity in Western countries. Depressive symptom scores did not differ significantly across BMI groups. However, MGSEM revealed distinct structural patterns. In the Middle BMI group, BMI showed a significant negative direct association with depressive symptoms, whereas the pathway from self-devaluation to depressive symptoms was attenuated in the High BMI group. Furthermore, a significant negative indirect effect of BMI on SESTA was observed exclusively in the High BMI group, suggesting that body weight itself may function as a barrier to healthcare engagement.