OBJECTIVE To assess the level of body dissatisfaction among undergraduate medical students in the city of Juiz de Fora, Minas Gerais, Brazil. METHODS A cross-sectional study with 232 volunteers of both sexes at a private college. The Body Shape Questionnaire was used, which is a tool based on the sum of values that allow classifying body dissatisfaction according to the following scores: less than 111, if absence of body dissatisfaction; between 111 and 138, if mild body dissatisfaction; between 139 and 167, if moderate body dissatisfaction, and from 168, if severe body dissatisfaction. In addition, the self-reported body mass index and an assertion were used to assess the degree and perception (insight) of body dissatisfaction. For the statistical analysis, descriptive comparison, and binary logistic regression tests were performed. RESULTS The mean result of the Body Shape Questionnaire among women was 96.0±34.1 and among men, 76.7±24.7, with 26.3% of students with some level of dissatisfaction with self-image. Most participants (76.3%) wished to have a body mass index lower than the real one. Women (odds ratio of 5.7), overweight individuals (odds ratio of 6.1), and individuals with insight into their condition (odds ratio of 89.7) were more likely to be dissatisfied with the body image measured by the Body Shape Questionnaire. CONCLUSIONS The search for a thin body among undergraduate medical students is a reality. In addition to overweight individuals, the female population has a significant level of body distortion, being recognized as the highest rate of body dissatisfaction in the sample surveyed.