Effectiveness of a Precision Diet Based on Gene Expression Versus a Personalized Mediterranean-Style Diet in Weight Loss

Calculated as weight (kg) divided by height (in squared meters), BMI= kg/m^2.

Measured as the percentage of body fat with a body composition analyzer (Inbody 120, Korea).

The RNA from fasting blood samples will be sequenced using Illumina technology and then the Limma software package will be used to analyze gene expression data from the RNA sequence.

Fasting measurement of triglycerides, total cholesterol, LDL-cholesterol and HDL-cholesterol (mmol/L) will be measured in venous blood with the standard methodology of the clinical analysis laboratory of the Hospital de Sant Pau.

Fasting measurement of glucose, insulin, and glycated hemoglobin (mmol/L) will be measured in venous blood with the standard methodology of the clinical analysis laboratory of the Hospital de Sant Pau.

Fasting measurement of CRP will be measured in venous blood with the standard methodology of the clinical analysis laboratory of the Hospital de Sant Pau.

Measured to the nearest 0.1 cm using a flexible steel anthropometric tape (CESCORF, Brazil) calibrated in centimeters.

Measured as the kilograms of muscle mass with a body composition analyzer (Inbody 120, Korea).

Measured in Metabolic Equivalents of Task (MET) per minute and week, using the short version of the International Physical Activity Questionnaire (IPAQ). The IPAQ consists of 7 questions that assess the frequency, duration, and intensity of physical activity (moderate and vigorous) performed in the last seven days, as well as walking and sitting time on a workday. The minimum value is 0 MET-minutes/week, indicating no physical activity. Higher scores represent a higher amount of physical activity, while lower scores indicate lower levels of physical activity.

Energy and nutrient intake will be assessed with a 151-item semi-quantitative food frequency questionnaire (FFQ) and a 3-day dietary record (DR), in which participants will record their food intake for three days. The frequency of consumption for each food item is reported on a nine-level incremental scale (never or almost never, 1-3 times per month, once per week, 2-4 times per week, 5-6 times per week, once per day, 2-3 times per day, 4-6 times per day and more than six times per day). To calculate energy and nutrient intake from both methods (FFQ and DR), the Spanish food composition tables will be used.

Diet quality will be evaluated through the 17-item Mediterranean Diet Adherence Screener (MEDAS). The score ranges from 0 to 17, where higher scores indicate greater adherence to the Mediterranean Diet.

Eating behaviors will be measured with the Spanish version of the Three Factor Eating Questionnaire (TFEQ-R21). It consists of three subscales: Cognitive Restraint (CR), Uncontrolled Eating (UE), and Emotional Eating (EE). Scores range from 0 to 21 for CR and UE, and from 0 to 15 for EE. Higher scores on each subscale indicate higher levels of the corresponding eating behavior.

Well-being will be measured with the Spanish version of the World Health Organization (WHO-5) Well-being Index. Scores range from 0 to 25, where higher scores indicate higher well-being.

Stress will be evaluated through the Perceived Stress Scale (PSS-10), validated for Spanish population. Scores range from 0 to 40, where higher scores indicate a higher level of perceived stress.

Anxiety and depression state will be measured by the Hospital Anxiety and Depression Scale (HADS), validated for Spanish population. It consists of two subscales: HADS-A, designed to detect anxious states, and HADS-D, designed to detect depressive states. Scores range from o to 21, where higher scores indicate greater levels of anxiety or depression.

Satiety will be evaluated using the Visual Analogue Scale (VAS) after each meal. Scores range from 0 to 100 mm, where higher scores indicate greater levels of satiety.