Background: Studies from various cultures show that a large number of adolescent girls have a wish to be thinner, and thus more often go on diets. The purpose of this longitudinal study was to examine if a wish to be thinner among Swedish girls contributes to the development of disturbed eating, and to describe motives for wishing to be thinner.

Methods: Following ethical approval (reg. no: 258/94; 2014/401) the Demographic and Dieting Questionnaire and the Eating Disorder Examination Questionnaire were used in a general population cohort of 7-11year-old-girls (n=462), 20 years later in October 2015.Threshold for DE was 1 SD above general population mean. Chi-square tests providing OR were used.

Results: A wish to be thinner during adolescence increases the likelihood 3-5 times to develop disturbed eating during the following 20-year period. Self-described motives for the wish to be thinner was to “correspond to the societal ideal” and to “dealing with difficulties”.

Conclusions: For prevention, it is of importance to detect girls who wish to be thinner as early as possible. By considering the girls’ motives, preventive efforts might be perceived as more meaningful and relevant to the girls at risk of developing eating disorders.