Purpose: This study was conducted to specify the differences in nutrition knowledge, dietary behaviors, physical activity, and self-efficacy behaviors based on obesity status among adolescents.Methods: In the study, descriptive-correlational design type was used. The sample of the study consisted of 530 adolescents and their parents selected among 5th grade students studying in five secondary schools by using the stratified random sampling method. The study data were collected using the Family Information Questionnaire, the Nutrition Knowledge Scale,the Diet Behavior Scale,the Children’s Dietary Self-Efficacy Scale and the Exercise Behavior Scale. Adolescents were assessed according to body mass index percentages in overweight - obese and normal weight groups in two groups. SPSS 22 program was used in the analysis of the data. For the data assessment, descriptive statistical methods (mean, median, number, percentage) were used. Pearson’s Chi-Square test was applied for comparison of categorical data. The t-test was performed in between-group comparison of parameters. Results: 50.9% of the adolescents were male and 30% of them n=(159) were found to be overweight and obese according to BMI. There was no significant difference between the BMI normal, and overweight/obese adolescents according to gender, age, income status and the mother’s educational level (p>0.05). The difference between BMI normal and overweight/obese children based on Father’s Educational Level, Mother’s BMI, and Father’s BMI values was significant. As educational level of the father and BMI value of mother and father increased, the rate of overweight-obese adolescents also increased (p<0.05). It was found that adolescents’ mean “physical activity behaviors” was 17.457 ± 3.732; “nutrition knowledge mean score” was 11,330 ± 3,258; “dietary self-efficacy” mean score was 5.138 ± 5.386; “dietary behavior” mean score was 3.694 ± 5.324. The adolescents’ physical activity behaviors were high, self-efficacy behaviors were good, and nutrition knowledge levels and dietary behaviors were at moderate level. Nutrition knowledge, dietary behaviors, and dietary self-efficacy of overweight and obese adolescents were found to be high (p<0.05). No significant difference was found among the groups based on physical activity behaviors (p>0.05). Conclusion: All adolescents' nutritional knowledge and nutritional behavior scores were moderate. Nutrition knowledge, nutritional behavior and nutrition self-efficacy scores were high in overweight / obese adolescents. This result may be due to the fact that adolescents and parents in the overweight and obese group are more cautious about nutritional behavior. It can be said that obese adolescents can not turn into information behaviors. Attempts can be made for this. In this regard, larger studies can be suggested.