A student's weight is a particularly important characteristic in physical education. Research has shown that physical education teachers and people working in this area are particularly likely to hold strong negative implicit biases toward overweight students and that these students tend to earn lower grades in physical education. Stereotypes of overweight people might color teachers' judgments of these students. In this study, we experimentally investigated whether overweight students received lower grades from physical education teachers on an exercise than normal weight students. We presented a verbal description of an exercise and asked teachers to grade a student's performance and to judge the student's social and working behaviors. Teachers gave lower grades to the overweight student, and regression analyses showed that their stereotypical beliefs predicted their judgments. Teachers' motivation to control prejudice had no relation to their judgments. Nonetheless, our results showed that the same performance was graded worse only because the student was overweight.