The dataset was created for the project "Cyberhate that targets people who are plus-size in the news: The role of bystanders in mitigating social pathologies (CYBERPLUS)". The data was collected between July 12 and July 26, 2024, from 1,030 young Czech people aged 16-25. The survey asked young people about their sociodemographic information, attitudes toward and perceptions of entitativity of three groups (overweight people, underweight people, people with physical disabilities), group identification, bystander appraisals and behavioural intentions, hate speech perception, and internet use. It included an experimental part in which the participants were exposed as bystanders to social media news posts about overweight people and comments under the posts. The dataset is accompanied by a data dictionary and a technical report.