OBJECTIVESTo examine the relationships between body image, body satisfaction and dieting behavior in the context of pubertal changes in Japanese preadolescents.

METHODSA cross-sectional study of dieting behavior among 5,244 preadolescents (2,452 boys and 2,792 girls aged 12-13) born in Toyama prefecture.

RESULTSThe percentages of those who perceived themselves fat, wanted to be thinner, and had tried dieting, which increased with body mass index (BMI), were significantly higher in girls than in boys (34.2% vs. 20.0%, 58.0% vs. 26.0%, and 17.3% vs. 5.7%, respectively). Independent of sex and BMI, those who wanted to be thinner and those who had tried dieting were more frequently observed in those who perceived themselves fat, and those who had tried dieting were more frequently observed in those who wanted to be thinner. Pubertal changes were significantly associated with dieting behavior, but their relationships to body image and body satisfaction differed between sexes; for boys, those who perceived themselves fat were more frequently observed in those without pubertal changes; whereas for girls, those who wanted to be thinner were more frequently observed in those with pubertal changes.

CONCLUSIONSDieting behavior of Japanese preadolescents was associated with whether they perceived themselves fat and wanted to be thinner, sometimes independent of whether they were actually overweight. Pubertal changes might induce a positive perspective of growing fat among boys and a desire to be thinner among girls, with the consequence that dieting behavior would be reinforced in those with pubertal changes.