The aim of the present study was to analyze the relationship between time spent engaged in sedentary behaviors, type of diet, and overweight in adolescents. A cross-sectional study using data from the Longitudinal Study on Sedentary Behavior, Physical Activity, Eating Habits, and Health of Adolescents--LONCAAFS Study. A total of 1,438 adolescents (10 to 14 years old) from public schools in the city of Joao Pessoa, Brazil, participated in the study. To evaluate the combined effects of excessive time in sedentary behavior and consumption from two food groups: Convenience and Prudent on overweight, we performed multiple logistic regression analyses, adjusted for energy, level of physical activity, sex, and age. Excessive time in sedentary behavior increased the chance of adolescents being overweight by 37% (OR = 1.37; 95%CI: 1.04-1.80). This chance increased to 43% when the adolescents were simultaneously engaged in excessive sedentary behavior and had high consumption of the Convenience food group (OR = 1.43; 95%CI: 1.05-1.94) and increased to 39% on those who engaged in excessive sedentary behavior and had low consumption of foods from the Prudent (OR = 1.39; 95%CI: 1.04-1.84). Excessive sedentary behavior is associated with being overweight and the chance increases with the consumption of convenient foods. Key words Overweight, Sedentary lifestyle, Diet, Adolescents O objetivo do estudo foi analisar a relacao entre tempo gasto em comportamentos sedentarios, dieta e excesso de peso em adolescentes. Estudo transversal com dados do Estudo Longitudinal sobre Comportamento Sedentario, Atividade Fisica, Habitos Alimentares e Saude do Adolescente--Estudo LONCAAFS. Participaram 1.438 adolescentes (10 a 14 anos) de escolas publicas de Joao Pessoa, Brasil. Para avaliar os efeitos combinados do tempo excessivo no comportamento sedentario e no consumo de dois grupos de alimentos: Conveniencia e Prudente sobre o excesso de peso, foram realizadas analises de regressao logistica multipla, ajustadas para energia, nivel de atividade fisica, sexo e idade. O tempo excessivo em comportamento sedentario aumentou em 37% a chance de os adolescentes apresentarem excesso de peso (OR = 1,37; IC95%: 1,041,80). Essa chance aumentou para 43% quando os adolescentes apresentaram, simultaneamente, comportamento sedentario excessivo e alto consumo do grupo de alimentos de conveniencia (OR = 1,43; IC95%: 1,05-1,94), e aumentou para 39% naqueles com excesso de comportamento sedentario e baixo consumo de alimentos do Prudente (OR = 1,39; IC95%: 1,04-1,84). O comportamento sedentario excessivo esta associado ao excesso de peso e a chance aumenta com o consumo de alimentos convenientes. Palavras-chave Excesso de peso, Comportamento sedentario, Dieta, Adolescentes