Prevalence and correlates of self-induced vomiting as weight-control strategy among adolescents in Taiwan

Aims. This study was designed to assess the prevalence and correlates of self-induced vomiting to control body weight among adolescents in Taiwan. Background. Over the past decades, the rate of obesity among children in Taiwan has nearly tripled. Educational authorities have devoted considerable effort to prevent the increase in childhood obesity. Design. An observational exploratory design to investigate the problem of using unhealthy weight-reduction strategy. Methods. This study consists of a cross-sectional study aimed at collecting national representative data. We chose 120 representative schools using a three-stage stratified systematic sampling design with probability proportionate to the size of the population in Taiwan. Participants consisted of 8673 girls and 7043 boys, aged 10-18 old. Results. Of the participants, 13% reported using self-induced vomiting, the prevalence being highest in participants aged 10-12 (15·9%) and lowest in participants aged 16-18 (7·5%). Several factors were significantly and positively associated with the use of self-induced vomiting as a weight-loss strategy, specifically subjects who (1) watched television, used computer, surfed the Internet or played video games for greater than or equal to twohours/day, (2) consumed fried food every day and (3) ate night-time snacks every day (odds ratio=1·55, 2·10 and 1·51, respectively; p<0·05). Eating breakfast every day and sleeping for more than eighthours a day were both protective factors against the use of self-induced vomiting to control body weight (odds ratio=0·43 and 0·86, respectively; p<0·05). Conclusions. Self-induced vomiting was prevalent among adolescents who had tried to lose weight; sedentary lifestyle, shorter sleep length and unhealthy eating habits may contribute significantly to this behaviour among these adolescents. Relevance to clinical practice. School nurses who are helping adolescents lose weight should also pay attention to the possibility they are using self-induced vomiting as a weight-control strategy.