Grant: Doctoral Research Award: Canada Graduate Scholarships

The prevalence of severe obesity has increased over the past 30 years, contributing to ~$4 billion in annual healthcare costs in Canada. Metabolic Bariatric Surgery (MBS) is the most efficacious intervention for severe obesity, leading to substantial improvements in comorbidities and long-term weight loss. However, some patients experience weight regain, recurrence of comorbidities, and less favourable psychological outcomes. Depression is the most common mental health condition among MBS patients, and increased postoperative depressive symptoms are linked to reduced weight loss. Although there is evidence connecting depressive symptoms to weight change following MBS, the directional relationship remains unclear. Additionally, it is uncertain which specific depressive symptom clusters-somatic, cognitive, or mood-are most associated with weight change. This proposal aims to examine the directional influence of depressive symptoms on weight outcomes following MBS and identify which symptoms are most relevant to post-surgical weight loss. This will be achieved using the Obesity-Related Behavioral Intervention Trials (ORBIT) framework across three key studies. The first study will assess whether reductions in depressive symptoms are linked to greater long-term weight loss and if this effect is stronger than the reverse in a local longitudinal cohort. The second study will replicate these findings in a larger, more diverse series of samples to increase generalisability. The third study will identify the specific depressive symptom clusters associated with reduced weight outcomes, thereby determining which symptoms should be prioritised for tailored interventions. The results from this research will provide key insights for assessing depression and creating tailored, evidence-informed interventions addressing depressive symptoms and long-term weight loss post-MBS.