Weight stigma is described as prejudice and discrimination concerning body weight. People stigmatized by their body weight report worse physical and mental health and, consequently, poor psychosocial functioning. Research has shown a high prevalence of weight stigma among health professionals. However, less is known about weight stigma among healthcare undergraduate students. In this vignette study, we assessed weight stigma in 217 healthcare students, who filled sociodemographic and weight stigma measures, and read one of three vignettes at random, each one with a hypothetical patient which differs only in terms of body weight (underweight, healthy weight, and overweight). Then, participants answered ten questions/statements about patient characteristics described in the vignette to assess the influence of body weight on stigmatizing beliefs. Weight stigma was found in 39.44% of healthcare students. Moreover, weight stigma was higher among men, healthy weight people, and Physical Therapy students. This experimental study showed more negative attitudes in participants exposed to the patient with overweight and underweight vignettes compared to those exposed to the healthy weight patient vignette. Due to the known impacts of weight stigma, efforts are needed to address this issue during the training of healthcare undergraduate students.