Children and teens who are overweight or obese are more likely to have asthma than their healthy-weight peers, a new study finds. The strength of the association between asthma and obesity varied by race and ethnicity. The strongest association between body-mass index (BMI), a measure of body fat based on height and weight, and asthma was found in Hispanic youth, while the link between being overweight or obese and having asthma was weakest in black children.