By studying cell tissue samples of patients that had heart surgery, scientists found a series of chemicals were released from certain body fats in the event of a heart attack or stroke, in response to warnings sent out by the heart and surrounding arteries.

London - Coughs, sneezes and a runny nose are not the worst a bad cold can do to you – it might also make you fat.

Scientists believe a virus behind the common cold could have fuelled the obesity epidemic that has swept the developed world.

The culprit? A contagious bug called adenovirus 36.

Experts told the European Congress on Obesity in Sofia that eating and exercise habits haven’t changed enough to explain why people worldwide started piling on weight at around the same time.

But they pointed out that the rise of obesity over the last 30 years has coincided with the discovery of the bug adenovirus 36. Highly infectious, it can cause mild coughs and colds.

And tests have shown that animals injected with the virus gained weight, even when their food intake stayed the same.

The virus worms its way into fat cells, where it instructs them to store more fat than usual.

It also tells stem cells, master cells with chameleon-like properties, to turn into fat cells.

The Czech researchers discovered that overweight and obese teenagers were up to two-and-a-half times as likely to have been infected with the bug than their slimmer counterparts.

And another study has found that roughly a third of those classified as obese have evidence of the bug in their systems.

Richard Atkinson, an American doctor who has devoted 15 years to the subject, believes the bug fuels weight gain for decades after someone catches it.

He said: “I think there is a very good likelihood that a significant proportion of the obesity epidemic is due to this virus.

“Potentially, it affects weight for more than 20 years. And worse than that, once you are fat, you are probably stuck, because once you have made all those new fat cells, they don’t just go away.”

Dr Atkinson has patented a formula for a vaccine to guard against adenovirus 36. But the idea that obesity is contagious is so unusual that he has not been able to get funding to develop the jab.

In the meantime, he advises those who want to stay adenovirus-free to keep their immunity high by getting enough sleep, avoiding stress and washing their hands.

And thin, rather than fat, people with colds should be given a wide berth.This is because the virus stops being infectious long before it starts to make someone gain weight. He said: “You are likelier not going to catch adenovirus 36 from a fat person – it is the skinny person with a cold that you have got to avoid.”

However Dr Irena Hainerova said: “Too much food and lack of exercise are the cornerstones of the obesity epidemic. The best advice is to eat healthily and move more.”

* A gene-based diet helped slimmers lose a third more weight, a study has shown. Diets were prepared for 87 obese people based on their genetic make-up. After two years they had lost 33 percent more weight than those whose diets were not adjusted. Dr Nicola Pirastu, from Trieste University in Italy said: “By uncovering genetic bases of food preferences, we will increase the effectiveness of nutritional interventions.” - Daily Mail