Aim: The main aim of the present study was to explore the potential associations between dietary habits and the presence of overweight and obesity in Chilean adolescents. Methods: For the present study dietary habits of 21,385 Chilean students were analyzed and weight and height assessed, in order to determine potential associations between eating patterns and body mass index (BMI) values. Results: The majority of participants have lunch and a snack in the afternoon every day a week (81% and 71.2%, respectively), although only a 59.5% have breakfast every day and a 22% have dinner every night. To have breakfast is common for thin and normal weight subjects, but only a half of overweight and obese individuals usually have it. The obese is the group having less dairy products. A 50.2% of all subjects have legumes once or never in a week. Around a 15% have sweets all days and nearly a 50% of all the participants consume fizzy drinks every day of the week. Interestingly, having breakfast was found to be associated with less truancy. Conclusions: Nutritional education strategies should be carried out within students in Chile, since inadequate dietary habits are related to the higher values of BMI.