Asthmatics are more likely to become obese, a new study found.

Being overweight or obese is a known risk factor for developing the respiratory condition.

But the new study found the reverse is true and having the condition can cause ypu to pile on the pounds.

And those who develop asthma as adults and those who have non-allergic asthma are at the greatest risk of obesity.

There are are 5.4 million asthmatic Britons or one in every 11.

A quarter of adults are obese, and rates have more than tripled in the last 30 years.

European Respiratory Society research fellow Dr Subhabrata Moitra at ISGlobal - the Barcelona Institute for Global Health - explained: "We already know that obesity can be a trigger for asthma, perhaps via a physiological, metabolic or inflammatory change.

"Until now there has been very little research on whether the reverse is true - whether asthma can lead to obesity.

"In this study, we have enough people and we have followed them for long enough to observe the relationship between these two conditions."

The research was part of the European Community Respiratory Health Survey and included 8,618 people from 12 countries who were not obese at the start of the research.

This means they all had a body mass index of less than 30kg/m2.

Being asthmatic was classified as those who have had asthma in the past, taking asthma medication or have had an asthma attack or were woken up by an attack of shortness of breath in the previous 12 months.

They were recruited from the 1990s and followed up at ten years and 20 years.

The study examined the relationships between having asthma at the start of the study and the likelihood of being obese ten years later.

They also studied people who had developed asthma after ten years and their risk of obesity by 20 years.

Other risk factors were taken into consideration, including age, sex, country and physical activity.

It found a tenth - 10.2 per cent - of people with asthma at the start of the study had become obese ten years on.

Among people who did not have asthma, a twelfth - 7.7 per cent - were obese ten years later.

Dr Moitra added: "By following a large number of study participants over two decades, we have been able to observe how having asthma increases a person's risk of going on to become obese, especially if their asthma begins in adulthood or if they have asthma but no allergies.

"Our findings suggest the relationship between the two conditions is more complicated than we previously realised.

"It's important that we do more work to pick this apart.

"For example, we do not know why having asthma increases the risk of developing obesity or whether different asthma treatments have any effect on this risk."

Professor Guy Brusselle from Ghent University and Chair of the European Respiratory Society Science Council.

Prof Brusselle, who was not involved in the study, commented, said: "With the right medication, many people with asthma gain good control of their symptoms.

"However, there is no cure for asthma and there is still a lot we do not know about its causes and its effects on the rest of the body.

"This research is an important step in helping us untangle the relationship between obesity and asthma but it also raises new questions about why the two are linked and what can be done to help patients."

The new research was presented at the European Respiratory Society International Congress in Paris.

ENDS