Test-retest reliability and discriminant validity of the Restraint Scale translated into Portuguese

The aim of this study was to evaluate reliability and discriminant validity of the Restraint Scale (RS) translated into Portuguese. The version was obtained through a process of translation and back translation. Women with eating disorders (n=39: 24 bulimics and 15 anorexics) and students without eating disorders (n=57) filled the scale. It was hypothesized that if the scale has any discriminant validity, the bulimic scores should differ from those of the students and the anorexics. The questionnaire was applied twice to the controls with 1-month interval to evaluate test-retest stability. Bulimics obtained a score of 28.1±13 (significantly different from students and anorexics), anorexics obtained 17.3±9 (significantly different from students), and students 11.3±5. Body mass index (BMI) was significantly correlated to dietary restraint, especially among controls. Test-retest correlation coefficient was .64 (P=.000001). The RS translated into Portuguese seems to be a valid and reliable instrument, which can be used in many studies of eating behaviors.