“Fat talk”, an emerging concept within the eating disorder literature, refers to normalized conversations that involve degradation of body shape, weight and size. Previous research suggests that these negative body comments have detrimental effects on body dissatisfaction, self-esteem, mood and dieting behaviors, but this research is fairly limited due to the absence of a standardized experimental manipulation of fat talk. The current study investigated the causal effects of fat talk on body dissatisfaction, self-esteem, mood and eating behavior, while also examining the potential moderating effects of three individual difference variables (i.e. self-esteem, neuroticism and dietary restraint). A pilot study (N = 30) evaluated the appropriateness of researcher-developed manipulations for “fat talk” and neutral conditions. In the main study, women undergraduates (N = 116) completed baseline measures of body dissatisfaction and self-esteem, and were subsequently randomized to fat talk or neutral conditions and were concurrently presented with a food stimulus. Results indicate that differences between the fat talk and neutral conditions on food consumption and changes in body dissatisfaction and self-esteem were not statistically significant. However, fat talk and neutral conditions did differ significantly on reported negative affect. Further, although neuroticism and self-esteem did not moderate the relationship between condition type and body dissatisfaction, this relationship was moderated by dietary restraint. These findings highlight the importance of individual vulnerability characteristics, and the continued need to develop standardized manipulations of fat talk.