Unnecessary Dieting Intention and Behavior among Female Students in Naha City, Japan.

Weight concerns and dieting are prevalent among female adolescents both in Western and Asian countries. They can result in negative psychological and physiological consequences. This study aimed to examine the relative importance of social and personal factors in the decision to diet among female adolescent students in Japan, applying the Theory of Planned Behavior. Data were collected from five junior high schools and three high schools in Naha City, Okinawa Prefecture, in 2010, through self-administered questionnaires. The data of 756 female students were assessed. The independent variables included social factor variables (norms) and personal factor variables (attitude to dieting, perceived behavior control, body esteem, body-figure discrepancy and past dieting). The dependent variables were dieting intention and behavior. Hierarchical multiple regression analyses were performed to examine three models: model 1 (age and obesity index), model 2 (social factor variables with age and obesity index) and model 3 (all variables). Although model 2 failed to explain a substantial proportion of the variance, model 3 explained approximately a half of the variance for intention (R(2) = 0.507) and more than one third of the variance for behavior (R(2) = 0.376). Past experience of dieting was the best predictor of both dieting intention and behavior. Body esteem was the second best predictor for dieting behavior. In conclusion, personal factors are more likely than social factors to drive the dieting decision. Diet education programs should consider targeting frequent dieters and those with poor body esteem.