Background:
Obesity has been identified as one of the major epidemics of the 21st century, with significant consequences for physical and psychological health. Recent evidence suggests that psychological factors such as stress, emotional regulation, and self-esteem play a crucial role in treatment adherence and effectiveness.

Participants and procedure:
This study followed a quasi-experimental longitudinal design. Sample of 129 adult patients diagnosed with overweight or obesity completed validated self-report measures assessing anxiety, depression, self-esteem and food craving. The sample was divided into control group and intervention group, with a six-month psychological intervention. Data analysis included ANOVAs and regression models.

Results:
The scores obtained in the baseline psychometric measurements showed significant differences after the psychological intervention, suggesting improvements in psychological variables associated with overweight and obesity.

Conclusions:
These results underscore the importance of including psychological strategies in weight loss treatments, as emotional state and body image can influence treatment adherence and success. The Mediterranean diet also contributes to BMI reduction, with no significant differences between genders or between overweight and obesity, suggesting that the psychological intervention can be applied homogeneously in these groups without the need for specific differentiation. Participants who voluntarily agreed to participate may have shown higher baseline motivation toward behavioral change. The findings should be interpreted with caution due to the non-randomized design and potential self-selection bias.