Mindfulness and Sustainable Food Choices.

• Mindfulness-based Intervention (Behavioral): The mindfulness-based intervention consists of a structured online program delivered over four weeks. Participants attend four 2-hour group sessions conducted once weekly. The program includes guided mindfulness practices, experiential exercises, and group discussions aimed at increasing awareness of eating behaviors, emotional triggers, and food-related decision-making.
• Nutritional Education (Other): The nutritional education intervention consists of two 1-hour online sessions delivered over two separate weeks. The sessions are based on the EAT-Lancet dietary recommendations for healthy and sustainable eating and provide evidence-based guidance on food choices and dietary patterns consistent with environmental sustainability and health promotion

Primary outcomes

• Change in adherence to the EAT-Lancet Diet [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in adherence to a healthy and sustainable dietary pattern, assessed using the EAT-Lancet Index. The index ranges from 0 to 42, with higher scores indicating greater adherence to the EAT-Lancet dietary recommendations. The total score is derived from 14 dietary components, each scored from 0 to 3. Adherence categories are defined as follows: ≤13 (low adherence), 14-16, 17-19, 20-22, and ≥23 (high adherence).

Secondary outcomes

• Change in MedQ-Sus score [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in Sustainable diet adherence assessed using the Mediterranean Diet Quality Index for Sustainability (MedQ-Sus; range: 0-8), with higher scores indicating greater adherence to a sustainable diet.
• Change in body weight and body mass index (BMI) [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in body weight measured in kilograms (kg) and in BMI calculated as weight (kg)/height (m²)
• Change in Mindfulness [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in mindfulness (awareness) assessed using the Awareness subscale of the Philadelphia Mindfulness Scale. Scores range from 10 to 50, with higher scores indicating greater awareness of the present momen.
• Change in mindful eating behaviors [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in mindful eating (awareness) assessed using the awareness subscale of the Mindful Eating Questionnaire. Mean scores range from 1 to 4, with higher scores indicating greater awareness of how food affects sensory experiences and internal states.
• Change in Psychological distress [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in depression symptoms assessed using the depression subscale of the Depression Anxiety Stress Scales-21 (DASS-21). Scores range from 0 to 42, with higher scores indicating greater symptom severity.
• Change in sleep quality [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in sleep quality assessed using the Mini Sleep Questionnaire. Total scores range from 10 to 70, with higher scores indicating poorer sleep quality.
• Change in Mindfulness [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in Mindfulness (acceptance) assessed using the Acceptance subscale of the Philadelphia Mindfulness Scale. Scores range from 10 to 50, with higher scores indicating greater acceptance (non-judgmental attitude toward experience).
• Change in Mindfulness [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in mindful eating (recognition) assessed using the recognition subscale of the Mindful Eating Questionnaire. Mean scores range from 1 to 4, with higher scores indicating greater ability to recognize hunger, satiety, and cues that lead to eating beyond physiological needs.
• Change in Psychological distress [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in anxiety symptoms assessed using the Anxiety subscale of the DASS-21. Scores range from 0 to 42, with higher scores indicating greater symptom severity.
• Change in Psychological distress [Baseline, 4 weeks and 8 weeks after the end of the nutritional education sessions]: Change in stress symptoms assessed using the stress subscale of the DASS-21. Scores range from 0 to 42, with higher scores indicating greater symptom severity.

Sex: All, ages: 18 Years to 35 Years

Inclusion Criteria:

* Aged 18 to 35 years;
* Low adherence to a sustainable diet, defined as a MedQ-Sus score ≤ 3.0;
* Body mass index (BMI) between 18.0 and 29.9 kg/m²;
* Able to provide written informed consent;
* Generally healthy volunteers;
* Omnivorous diet;
* No current or past history of eating disorders;
* Not pregnant and not planning pregnancy during the study period;
* Personally responsible for making food-related decisions.

Exclusion Criteria:

* MedQ-Sus score ≥ 3.1;
* BMI < 18.0 or > 29.9 kg/m²;
* Unable to provide informed consent;
* Dietary restrictions;
* Allergy or intolerance to the tested food.

• Informed Consent Form (PDF, 2024-07-07)