Analysis of the associations of obesity, percentage of body fat and visceral fat mass with body iron status in 1,493 schoolchildren aged 9–13 years shows that boys and girls with obesity have higher serum ferritin levels and lower transferrin saturation levels than normal-weight children. Iron deficiency and iron-deficiency anemia were more frequent in boys and girls in the highest quartiles of percentage of body fat than in children in the lowest quartile, possibly owing to the chronic inflammation induced by excessive adiposity.