The effect of MEditerranean DIet and MINdfulness eating on Depression severity in people with major depressive disorder and obesity (MEDIMIND): a study protocol of a randomised controlled clinical trial with multifactorial design.

Obesity and depression are highly prevalent diseases that are strongly correlated. At the same time, there is a growing gap in care, and treatment options should be improved and extended. Positive effects of a Mediterranean diet on mental health have already been shown in various studies. In addition to the physiological effects of nutrients, the way food is eaten, such as mindful eating, seems to play a role. The present study investigates the effect of a Mediterranean diet and mindful eating on depression severity in people with clinically diagnosed major depressive disorder and obesity. Participants will be randomised to one of the four intervention groups (Mediterranean diet, mindful eating, their combination and a befriending control group). The factorial design allows investigating individual effects as well as potential synergistic effects of the interventions. The study consists of a 12-week intervention period, where five individual appointments will take place, followed by a 12-week follow-up. The primary outcome is depression severity. Secondary outcomes are remission of depression, assessor-rated depression severity, quality of life, self-efficacy, BMI, waist:hip ratio and body composition; adherence to the Mediterranean diet and mindful eating will also be assessed. Alongside mediator and moderator analysis, a microbiome analysis, a qualitative evaluation and an economic analysis will be conducted. The study investigates an important health issue in a vulnerable target group. It allows to draw valuable conclusions regarding the effectiveness of different interventions and therefore contributes to improving available care options for people suffering from depression and obesity.