Obese people are drowning in their own fat, as it blocks airways in the lungs, research suggests. A new study provides the first evidence that fat can accumulate in the airway walls, hindering efforts to breathe.

Scientists already know that people who are overweight or obese are more likely to suffer with wheezing and asthma, but the reasons for this have not been completely explained.

The new study, published in the European Respiratory Journal, suggests that the fatty tissue alters the structure of people's airways - and could be one reason behind the increased risk of asthma.

Study author John Elliot, a senior research officer at Sir Charles Gairdner Hospital in Perth, Australia, said: "Our research team studies the structure of the airways within our lungs and how these are altered in people with respiratory disease.

"Looking at samples of lung, we spotted fatty tissue that had built up in the airway walls.

"We wanted to see if this accumulation was correlated with body weight."

The researchers examined post-mortem samples of lung that had been donated for research and stored.

They studied samples from 52 people, including 15 who had no reported asthma, 21 who had asthma but died of other causes and 16 who died of asthma.