ABSTRACT Objective To examine the association of body image dissatisfaction (BID) with body mass index (BMI) trajectory among students from a metropolitan area of Rio de Janeiro. Methods Data were analyzed for 809 middle school students followed from 2010 to 2013, and 1131 high school students followed from 2010 to 2012. BID was assessed using a body silhouettes scale. Type of school (public and private) was used as a proxy of socioeconomic status. Results In the middle school cohort, girls from private schools who wanted to have smaller and bigger silhouettes gained fewer BMI units than those who were satisfied with their body image ( p < 0.05). In the high school, girls from private schools who wished to have bigger and smaller silhouettes experienced greater BMI increase than girls who were satisfied with their body image ( p < 0.05). Also, in the high school cohort, boys from public schools who wished to have smaller and bigger silhouettes experienced smaller BMI increase than boys who were satisfied ( p < 0.05). Conclusion BID may be related to the BMI trajectory in girls from private schools and in boys from public schools.