This study aimed to evaluate the influence of food advertising and television exposure on eating behaviour and nutritional status of children and adolescents. It was a cross sectional study developed among 116 students from a private school in Brazil. Socio-demographic and health conditions were evaluated. Anthropometric data, food consumption, physical activity, television viewing habits and behaviour in relation to food advertising were also investigated. Among the results, a 1:2 relationship was identified between the number of televisions and residents per household. Excessive weight was present in 25.8% of subjects and 66.4% of children watched television while eating. Children were exposed to television for a median of 3.0 hours daily (95% CI: 2.9 to 3.6). There was a direct association between attraction to foods advertised and purchasing the product (p < 0.001) and a positive relationship between the number of televisions per household and body weight (r = 0.246, p = 0.015) and the amount of liquid consumed during meals (r = 0.277, p = 0.013). Findings also highlighted the association between watching television while eating and the reduced probability of fruit consumption (p = 0.032), contrasted with a greater likelihood of daily artificial juice intake (p = 0.039). In conclusion, watching television is associated with lower probability of daily consumption of fruits and the number of television at household is positively related to BMI in children and adolescents.