Introduction: Studies on lifestyle, nutritional status and body satisfaction of adolescents are important in the construction of educational strategies and health-related productions. Objective: The aim of this study was to compare and associate body mass index (BMI), some lifestyle factors and body image of adolescent schoolchildren. Materials and Methods: For this, 60 students (14.65 +/- 1.36 years) completed a questionnaire to collect sociodemographic and lifestyle data, had their body mass and height measured, and answered the body satisfaction scale of Stunkard silhouettes. The data were analyzed using the independent Student T-test and a linear regression. The significance level adopted was p<0.05. Results: The results revealed lower BMI for participants who practiced exercise (19.33 +/- 2.73 vs. 21.49 +/- 2.39 kg/m(2); p=0.002) and who did not consume alcoholic beverages (20.18 +/- 2.69 vs. 22.42 +/- 6.63 kg/m(2); p=0.043). A significant negative correlation was observed between BMI and body satisfaction (r=-0.558; p<0.001) and BMI explained 30.0% of the participants' body perception. In addition, it was possible to identify that, of the participants, 78.3% have body dissatisfaction. Discussion: Although most had adequate BMI, it was observed that body dissatisfaction was characterized, for the most part, for thinness, a finding different from most studies. Conclusion: It is concluded that lifestyle can affect BMI of schoolchildren and that BMI is able to predict, negatively, the perception of body satisfaction of adolescents.