The dynamics of change in eating behavior are dependent on changes in the perception and attitudes of the subjects under the action of a multiplicity of factors, resulting from the appropriate psychological and psychotherapeutic intervention. Objective: To study the changes made in the psychological functionality of children and adolescents with overweight/obesity under the action of psychological intervention. Research typology: Quantitative quasi-experimental study and comparative approach between two moments: before and after the psychological intervention. Participants: 20 children and adolescents of both sexes diagnosed with overweight/obesity. Methodological instruments: Clinical-psychological interview; sociodemographic questionnaire; eating behavior questionnaire (EBQ); eating disorder inventory (EDI). Results: Overweight/obese children and adolescents, after undergoing psychological intervention actions, about eating behavior present significantly more expressive values in attitudes oriented towards food restriction and less expressive in attitudes oriented towards external and emotional food intake. In the triad of scales of eating disorders, the values are more expressive in terms of concern (obsession) with weight loss and body dissatisfaction and less expressive in attitudes oriented towards bulimic behavior. In the individual psychological characteristics: the feeling of ineffectiveness, perfectionism, interpersonal distrust, interoceptive awareness, fear of maturity, asceticism, impulsiveness, and social insecurity, there are no statistically significant differences; minute variability. Conclusion: The psychological intervention in children and adolescents with overweight/obesity brought about changes in terms of ideas, perception, and attitudes, regarding eating behavior. Changes made in the dimensions related to the subjects' behavior regarding the process of control and management of food intake, not being detected in the individual characteristics inherent to the psychic functionality. Changes in perception and attitudes show that they are reactive, situational, and circumstantial, as there is no glimpse of an effective change in the problematic pattern.