Fatty tissue has been found in the lungs of overweight and obese people for the first time.
Australian researchers analysed lung samples from 52 people and found the amount of fat increased in line with body mass index.
They said their findings could explain why being overweight or obese increased asthma risk.
Lung experts said it would be interesting to see if the effect could be reversed by weight loss.
In the study, published in the European Respiratory Journal, scientists looked at post-mortem samples of lung donated for research.
Fifteen had had no reported asthma, 21 had asthma but died of other causes and 16 died of the condition.
The scientists used dyes to carry out detailed analyses of almost 1,400 airways from the ...