OBJECTIVE. To examine the relationships between body weight perceptions, estimated body mass index, gender, and weight control behaviours.

DESIGN. Cross-sectional survey.

SETTING. Three secondary schools in Hong Kong.

PARTICIPANTS. A total of 1132 secondary school forms 1 and 3 students.

MAIN OUTCOME MEASURES. The strength of agreement between perceived weight and estimated body mass index, and the association between perceived weight, estimated body mass index, and weight control behaviours.

RESULTS. A total of 14% of students were estimated to be overweight or obese. The agreement between actual (estimated) body mass index and perceived weight was poor in females and fair in males (Kappa 0.137 and 0.225, respectively). In females, there was no evidence of a relationship between body mass index and weight control behaviours. However, there was a relationship between perceived weight and weight control behaviours such that females who perceived themselves as overweight were more likely to exercise, restrict caloric intake, self medicate with diet pills, purge, or use laxatives. In males, there was evidence of a relationship between perceived weight, body mass index, and weight control behaviours. Males who perceived themselves as overweight or were overweight, were more likely to exercise or restrict caloric intake.

CONCLUSIONS. Body weight perceptions are not in agreement with actual weight in adolescents. This discrepancy is more marked in females who use a variety of weight control behaviours. These behaviours are motivated by perceived weight rather than actual (estimated) body mass index. Overweight adolescents should be encouraged to adopt appropriate weight control behaviours for their health needs.

Key words: Adolescent; Body image; Body Weight; Obesity; Weight loss

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