['To verify the prevalence of iron deficiency anemia according to sexual maturation stages and its association with overweight as well as excessive body fat in adolescents.', 'A school-based cross-sectional study was performed. Anemia was assessed by measuring the hemoglobin level (Hb). Nutritional status was defined by sex and age specific body mass index (BMI) cutoffs, and body fat (BF) was determined by bioelectrical impedance. Sexual maturation was assessed by breasts/genitalia and pubic hair development stages. Statistical analyses considered the effect of cluster sampling design (classes) and sampling expansion corrected by relative weight. Odds ratio and general linear modeling were used to assess the associations, regarding the value of p < 0.05 for statistical significance.', 'Public schools in the Metropolitan area of Rio de Janeiro, Brazil.', 'Probabilistic sample of 707 teenagers between 11.0 and 19.9 years old.', 'The prevalence of anemia among the adolescents was 22.8% (95%CI 16.7-30.2%), higher among girls than among boys (30.9% vs. 10.9%; p < 0.01). The chance of developing anemia did not change with the nutritional status according BMI or BF percentage, however, overweight girls presented lower Hb levels than those who were not overweight (12.2 g/dL vs. 12.8 g/dL, p < 0.01). In boys this association was not observed. Sexual maturation did not change the association of Hb and anemia with overweight and excessive body fat.'] Is overweight associated with low hemoglobin levels in adolescent girls?