Advertisements often display ideal female bodies which create unattainable standards of beauty, generating body anxiety and disorders in female viewers. Accordingly, public health concerns would encourage the use of natural, unedited models in advertisements. However, the advertising performance of natural models remains contentious. We argue that previous inconsistent findings about this performance may result from a complex causal framework in which natural models impact performance through two affective mediators (body anxiety, and repulsion toward the model), while allowing moderation by the viewer's own body mass index (BMI). Data collected in a nationally representative sample of 400 young women largely (but not entirely) validate this causal framework. Natural models triggered repulsion in viewers with higher BMI, which hurt advertising performance. Body anxiety, however, was positively correlated with advertising performance, and did not mediate any effect of natural models.