BACKGROUND: There is evidence for a relation of TV viewing with adiposity and increased cardiometabolic risk factors in children and adolescents. It is unclear to what extent this relation is mediated by snacking and lack of physical activity. We determined whether associations of screen time with adiposity and cardiometabolic markers were mediated by these behaviours. METHODS: Children from a population-representative Dutch birth cohort (n = 1447) reported screen time and other lifestyle factors by a questionnaire around the age of 11 years (range 10-14) and had anthropometry and cardiometabolic markers measured around the age of 12 years (range 12-14). Adjusted associations of screen time with snacking, physical activity, adiposity and cardiometabolic markers (total-to-high-density lipoprotein cholesterol (TC/HDLC)ratio, blood pressure, glycated haemoglobin) were assessed by using formal mediation analysis. We tested the hypothesized paths by structural equation modeling, which allows quantification of the indirect effects associated with potential mediators. RESULTS: Children with. 20 h screen time per week consumed more snacks (1.9 vs 1.3 portions per day) and were less physically active (4.3 vs 4.8 days per week) than children with maximum 6 h screen time. Screen time was directly associated with higher adiposity (standardized beta = 0.10-0.12 depending on the outcome, P