Background/Objectives:The objectives of this study were to investigate the relationship between inflammatory parameters (CRP, c-reactive protein; AGP, α1-acid glycoprotein), iron status indicators (SF, serum ferritin; sTfR, soluble transferrin receptor) and body mass index (BMI) z-score, fat-free mass (FFM) and fat mass (FM) in European adolescents. Differences in intake for some nutrients (total iron, haem and non-haem iron, vitamin C, calcium, proteins) were assessed according to BMI categories, and the association of nutrient intakes with BMI z-score, FM and FFM was evaluated.Methods:A total of 876 adolescents participating in the Healthy Lifestyle in Europe by Nutrition in Adolescence-Cross Sectional Study were included in the study sample.Results:Mean CRP values (standard error; s.e.) were significantly higher in overweight/obese adolescents (1.7±0.3 and 1.4±0.3 mg/l in boys and girls, respectively) than in thin/normal-weight adolescents (1.1±0.2 and 1.0±0.1 mg/l in boys and girls, respectively) (P<0.05). For boys, mean SF values (s.e.) were significantly higher in overweight/obese adolescents (46.9±2.7 μg/l) than in thin/normal-weight adolescents (35.7±1.7 μg/l) (P<0.001), whereas median sTfR values did not differ among BMI categories for both boys and girls. Multilevel regression analyses showed that BMI z-score and FM were significantly related to CRP and AGP (P<0.05). Dietary variables did not differ significantly among BMI categories, except for the intake of vegetable proteins, which, for boys, was higher in thin/normal-weight adolescents than in overweight/obese adolescents (P<0.05).Conclusions:The adiposity of the European adolescents was sufficient to cause chronic inflammation but not sufficient to impair iron status and cause iron deficiency.