Modeling the effect of weight stigma on weight management behaviors and psychological distress among young adults : a prospective study

Abstract

Overweight and obesity are significant global public health concerns. There are various psychosocial factors associated with these weight-related issues and how individuals manage their weight. One crucial factor is weight-related stigma, which refers to the devaluation and discrimination experienced due to body weight and is pervasive. Numerous researchers have raised concerns that weight stigma can lead to adverse health outcomes and exacerbate weight problems in a detrimental cycle. Nevertheless, there is a lack of empirical evidence to support these theories on whether weight stigma perpetuates problems in health and well-being. This thesis proposes that weight stigma, psychological distress, physical activity (PA), eating behaviors, and weight changes are interconnected, and weight stigma and weight changes potentially result in a feedback loop. This thesis consists of three studies. Applying the Theory of Planned Behavior (TPB) model, two cross-sectional studies (Studies 1 and 2) investigated how weight-related self-stigma (WRSS) could influence PA and eating behaviors. Additionally, a one-year longitudinal study (Study 3) examined how stigma is linked to changes in body mass index (BMI), with an emphasis on the growth trajectories and the interplay of these trajectories over time. Study 3 further examined how WRSS and BMI can predict changes in each other across time points. All participants were young adults. There were 325 and 348 participants in Studies 1 and 2. Study 3 had 345 participants in Time 1 and was able to retain 232 to 251 participants in the subsequent time points. Participants completed self-reported standardized questionnaires. Structural equation modeling, parallel process latent growth curve modeling, and random intercept cross-lagged panel model were used in this thesis. Study 1 indicated that WRSS significantly affected perceived behavioral control on PA (PBC-PA), intentions, and PA engagement, especially in overweight individuals. Study 2 showed that WRSS reduced perceived behavioral control for avoiding eating behaviors (PBC-EB) and increased uncontrolled and emotional eating. Study 3 further found that individuals with high WRSS exhibited higher BMI, perceived weight stigma, psychological distress, and eating behaviors compared to the low WRSS group. Furthermore, the high WRSS group had consistently lower PBC-PA and PBC-EB. Temporal relationships were only found in the associations among perceived weight stigma and WRSS, WRSS and psychological distress, PBC-PA and psychological distress, and WRSS and PBC-EB. In sum, the growth trajectories of the variables were not associated with BMI changes, but WRSS was negatively associated with subsequent BMI in another analysis. This thesis consistently demonstrated the adverse effects of WRSS on individuals' PA and eating behaviors. The proposed models indicated that PBC was the primary variable affected by WRSS, which may hinder engagement in PA and avoiding unhealthy eating practices. Furthermore, the relationship between WRSS and reduced PBC was significant in individuals who were overweight or not. Additionally, the research identified temporal associations between WRSS, perceived behavioral control, and psychological distress. However, the thesis did not find strong evidence to support the hypothesized feedback loop between WRSS and BMI. Further research is required to better understand whether weight stigma can be influenced by weight change.