The Health Behaviour in School-aged Children (HBSC) study is a large school-based survey carried out every four years in collaboration with the WHO Regional Office for Europe. HBSC data are used at national/regional and international levels to gain new insights into adolescent health and well-being, understand the social determinants of health and inform policy and practice to improve young people’s lives. The 2021/2022 HBSC survey data are accompanied by a series of volumes that summarize the key findings around specific health topics. This report, Volume 4 in the series, focuses on adolescents’ physical activity, eating behaviours, weight status and body image, using the unique HBSC evidence on adolescents aged 11, 13 and 15 years across 44 countries and regions in Europe, central Asia and Canada. It examines the status of moderate-to-vigorous and vigorous physical activity, physical inactivity, food and drink consumption, over- and underweight and body image among adolescents, explores the role of gender, age and social inequality and identifies how these adolescent behaviours have changed over time. Findings from the 2021/2022 HBSC survey provide an important evidence benchmark for current research, intervention and policy-planning.