This 12-week pilot study aims to evaluate the feasibility and effectiveness of a dietary intervention targeting diet, obesity, mental health, and the gut microbiome in promoting weight loss and enhancing mental health among obese men and women aged 30-50. Participants, excluding those with specific medical conditions, will be randomly assigned to either an intervention or control group using a meal planning smartphone app. Clinical assessments will include anthropometry, mental health questionnaires, dietary recalls, and stool sample collections. The study's endpoints include program retention, adherence, changes in body weight, mental health, and gut microbiome diversity. Statistical analyses will evaluate intervention effects and the potential mediating roles of the gut microbiome. This pilot study has implications for health policies, public healthcare, digital health companies, and the biotech and pharmacology industries. Future plans involve a large-scale intervention study in multiple countries with ongoing collaborations.

Objective of the Pilot Study and Study Design:

This 12-week randomized pilot intervention study aims to assess the feasibility and effectiveness of a dietary intervention targeting diet, obesity, mental health, and the gut microbiome in promoting weight loss and enhancing mental health among obese individuals aged 30-50.

Participant Recruitment and Randomization:

Participants aged 30-50, excluding those with specific medical conditions such as psychiatric medication use, food allergies affecting diets, eating disorders, diabetes, polycystic ovary syndrome, sensory deficits, recent antibiotic use, participation in other studies, language limitations, coeliac/inflammatory bowel disease, planned weight management within 3 months, and pregnant/lactating/post-menopausal women, will be recruited for the study. Randomization will be conducted to assign eligible participants to either an intervention or control group using a meal planning smartphone app.

Clinical Assessments:

Clinical assessments will include anthropometry, mental health questionnaires, dietary recalls, and stool sample collections.

Study Endpoints:

The study's endpoints include program retention, adherence, changes in body weight, mental health, and gut microbiome diversity.

Statistical Analyses:

Statistical analyses will evaluate the study feasibility, intervention effects on body weight and mental health changes, and the potential mediating roles of these effects by the gut microbiome.

Implications and Future Plans:

This pilot study has implications for health policies, public healthcare, digital health companies, and the biotech and pharmacology industries. Future plans involve a large-scale intervention study in multiple countries with ongoing collaborations.

Inclusion Criteria:

• age 30- 50;
• BMI ≥ 30 kg/m2;
• stable physical activity;
• one person per household;
• commitment to full protocol.

Exclusion Criteria:

• use of psychiatric medications (e.g., serotonin reuptake inhibitors);
• use of weight loss medications (GLP-1 receptor agonists);
• food allergies affecting adherence to the MIND diet;
• diagnosis of eating disorders;
• diagnosis of diabetes;
• diagnosis of polycystic ovary syndrome;
• sensory deficits (e.g., COVID-19-induced loss of taste/smell);
• antibiotic use during the latest 3 months;
• participation in another study;
• language understanding limitations (i.e., not able to understand either Swedish or English); - coeliac/inflammatory bowel disease;
• planned weight management program within three months;
• pregnancy;
• lactation;
• menopause.

Participants will be blinded to their group assignment and will use a smartphone app for meal planning. However, those in the intervention group may have some awareness of their assignment due to specific food choices. Meanwhile, the control group will have access to a variety of foods and recipes, maintaining blinding between the groups regarding their assigned diets, addressing a common challenge in diet intervention studies.