Objectives Correlational research has found associations between magazine and television exposure and body dissatisfaction. However, this relation is not direct, and various psychological variables may moderate and/or mediate this relation, such as awareness and internalization of the thin ideals, comparing oneself with ideal body image or self-esteem, as well as the patient’s body mass index (BMI). The aim of this study was to assess the association between magazine and television exposure and body dissatisfaction among Spanish adolescents by gender. A second aim was to determine the predictors of body dissatisfaction by gender. Methods A cross-sectional national survey of 1,165 Spanish secondary students aged 14 to 16 years was conducted. Frequency exposure and type of TV program/magazine as well as other psychological variables, such as thin-ideal internalization and self-esteem, were associated with high levels of body dissatisfaction (BD) based on a cutoff point of 16 or above on the Eating Disorder Inventory (EDI) by gender. Multiple linear regressions were used to examine associations between body dissatisfaction, mass media topic exposure, BMI, and psychological variables. Results Mass media exposure to a specific kind of content, rather than to total exposure frequency, was more associated with body dissatisfaction in females versus males. In males, five factors accounted for 35% of the total variance of body dissatisfaction and were associated with lower TV and magazine exposure to fitness topics and lower self-esteem and with greater BMI, disordered eating behaviors, and awareness of the thin ideal. For females, high body dissatisfaction was associated with greater internalization of the thin ideal, disordered eating behaviors, BMI, and lower self-esteem (54% of total variance explained). Conclusion There does not seem to be a clear association between media exposure and body dissatisfaction. Further research is necessary to enhance our understanding of how the media’s role affects adolescents’ awareness and internalization of the thin ideals, which may in turn lead to the development of body dissatisfaction and unhealthy weight control behaviors.