Non-communicable diseases (NCD) are the main health challenge in industrialized countries. However, these diseases are preventable if an intervention based on lifestyle is implemented at the population level. Diet has a great impact on the onset and progression of NCD. In this regard, ultra-processed food (UPF) consumption has been related to higher morbidity and mortality. UPF are defined as "formulations made mostly or entirely from substances derived from foods and additives, with little if any intact unprocessed or minimally processed foods" (NOVA definition). UPF are rich in saturated fats and additives and poor in fiber other nutrients. UPF consumption has raised in the last decades in the industrialized countries and this increase has been associated with higher prevalence of metabolic disorders such as diabetes, obesity, metabolic syndrome, cardiovascular disease, and cancer. However, mechanisms that link UPF consumption with NCD are poorly understood and clinical trials are needed to unravel these mechanisms and how to impact on them through lifestyle interventions. The investigators have previously identified DNA methylation marks associated with UPF consumption. DNA methylation marks are modifiable. The aim of the study is to assay if DNA methylation marks related to UPF consumption are reversible by reducing UPF consumption in a population of adults with overweight or obesity and with a high basal UPF consumption (>35% of total food consumption in g/day).

The investigators propose a controlled, randomized, parallel groups intervention study based on nutritional counseling to reduce UPF consumption. Eligible participants are adults (18-50 years old), men and women, with overweight or obesity (BMI 25-40 Kg/m2) with a high basal consumption of UPF (>35% of total intake in g/day).

Recruited participants will be randomly allocated into a control group or an intervention group. Participants in the control group will be provided with nutritional guidelines to follow a healthy diet based on a Mediterranean diet. Participants in the intervention group will follow a nutritional intervention program aimed to reduce UPF consumption. Nutritional intervention will not modify basal caloric intake but will record energy intake along the intervention. Nutritional counseling will be based on nutritional educational material such as encourage and discourage food items, recipes, menus and food shopping lists based on unprocessed or minimally processed foods.

Total intervention will last 6 months for both groups. During the intervention phase, a monthly interview with nutritionist/dietitian is scheduled. Face-to-face interviews will be carried out in months 2 and 4. Phone interviews will be carried out in months 1, 3 and 5. In the baseline and final visits (months 0 and 6) a sample and data collection will be performed.

Data collected will include general socio-demographical data (age, sex, educational level, working status, civil status, rural/urban status), lifestyle data (smoking habits, dietary habits, physical activity, sleeping habits), anthropometric data (height, weight, waist circumference, body composition), and clinic-phenotypical parameters (blood pressure, medication, adverse effects, disease prevalence). Biological sample collection will include blood, urine, saliva and feces. Biochemical and blood cells parameters will be measured (blood cell count, glucose, lipid and hepatic profiles).

Inclusion Criteria:

• Men/women
• 18-50 years old
• BMI 25-40 Kg/m2
• UPF consumption > 35% of total intake in g/day

Exclusion Criteria:

• Pregnancy
• Menopause
• IMC <25 Kg/m2 or > 40 Kg/m2
• Excessive alcohol consumption
• Prevalent cardiovascular, renal, lung, pancreatic or liver disease
• Type 1 diabetes
• Type 2 diabetes with poor glucose control or unstable medication during last 3 months
• Prevalent endocrine disease
• Changes in anti-hypertensive medication during last 3 months
• Insulin, systemic anti-inflammatory, or glucocorticoid medication during last 3 months
• Food allergies or intolerances
• Psychosocial or cultural factors that prevent from following the intervention

Informed consent does not allow to make data publicly available. Nevertheless, data could be share upon request to the investigators.

The investigator who will analyze data will be provided with blinded data regarding the groups. Control and intervention groups will be randomly designated as group A and B. Investigator responsible for the analyses of the effect of the intervention on primary outcomes will compared groups A and B in a blinded manner.