This study examined the relationship between perceived obesity threats, social support, and college students' eating attitudes and behaviors. Results showed that perceived vulnerability to obesity negatively predicted healthy eating behavior. In addition, the perceived severity of obesity-related health problems positively predicted women's drive for thinness. Social support played a significant role in explaining health behaviors. Specifically, appraisal by others indirectly predicted college students' healthy eating behavior through increased self-efficacy. Among women, informational support moderated the relationships between both vulnerability and severity on healthy eating behavior. At low levels of support, vulnerability and severity negatively predicted students' healthy eating behavior. Overall, results suggest that messages designed to increase perceived vulnerability and severity may be detrimental when trying to improve people's dietary habits; however, among women certain types of social support may buffer the defensive responses resulting from obesity threats.