Background: Considering the importance of adolescent obesity on adulthood health, this cross-sectional study aimed 408 students aged 13-18 years from different socioeconomic districts through convenience sampling to investigate nutritional status and physical activity (PA) level focusing on sex and socioeconomic differences. Methods: Weight and height were measured to investigate prevalence of obesity and underweight based on percentile of body mass index (BMI) for age. Information on dietary intake were collected via 3-day food recalls. PA level was investigated using a valid and reliable questionnaire. Results: The prevalence of underweight, overweight, and obesity were 4.9%, 15.9% and 23%, respectively. Weight and height were higher in boys than girls significantly (P-value < 0.001). Calorie intake in prosperous districts was higher than semi-prosperous districts (P = 0.01). Intake of zinc and calcium in prosperous districts was higher than semi-prosperous and disadvantaged districts (P-value < 0.001 and 0.02, respectively). Intake of calcium and zinc in both sexes and iron in girls, was lower than recommended dietary allowances (RDA) in all districts (P-value < 0.001). Conclusions: High prevalence of obesity and low micronutrients intake, especially in disadvantaged districts, suggest an urgent need to plan many efficient programs to prevent serious problems in future.