Nikhil Dhurandhar, an associate professor at the Pennington Biomedical Research Center in Baton Rouge, La., says the virus, known as AD-36, or the Adeno virus, infects the lungs, then whisks around the body, prompting fat cells to multiply and causing sore throats and coughs.
In one test, a-third of obese people had it, compared to 11 percent of thinner people.
Evidence in tests on mice and chickens points to the bug causing people to gain weight.
On The Early Show Tuesday, obesity expert Dr. Louise Aronne of New York-Presbyterian Weill Cornell Medical Center told co-anchor Julie Chen, "What this research shows is that a common cold virus can make people gain weight. This is a virus that people can get, and it's been shown to cause fat cells to reproduce, and it looks like what it does is it makes fat cells sort of suck fat into them. And that could make you gain more weight.
"I don't want people to be worried that they could actually catch it. We think that this is very, very uncommon. If anything, it may make you gain a little bit of weight. It's not that you're going to gain a tremendous amount of weight. But I think it shows that there's a lot of science to body weight regulation and obesity."
Aronne added, "It's a cold virus like any other. And so it looks like it could be transmitted. It's never really been shown how it's transmitted."
Can we come up with a vaccine for it?
"Potentially, but it's not everyone who's obese. That's not the case. Some people have it, not everybody."
Aronne pointed out, "There are blood tests that you could do to test if you have it. And people who have this seem to have a very low cholesterol level. And that is typical when someone has a lot of extra fat cells.
"We've actually seen patients who have a story that would be typical of having an infection and then they gain weight, sort of out of nowhere.
"We treat it the exact same way we treat all problems with weight. Through diet, exercise, there are some medical treatments and surgery. So this does not change treatment at all. That's the problem."
Aronne says the virus is active "for about three months. So we think that, for a period of three months, you might be gaining weight. But we really -- it's still premature to determine how we would best treat this problem.
" ... If we are able to diagnose it and we don't routinely do that, although there are blood tests, we don't routinely diagnose it, the thing to do would be to try to remain weight stable while you have it because otherwise the weight gain would be permanent."