According to scientists from Louisiana State University, obesity could be caused by a virus .

This was one of those medical findings that you knew would be featured both on the evening news and then a few minutes later on the late-night talk show monologues: Where do you catch this virus? At fast-food restaurants, of course. Perhaps we need to wash our hands more carefully with anti-viral wipes before eating a Big Mac.

But we can't just laugh this one off. There is some intriguing science behind the so-called fat virus.

Food or food-borne bug?

Few doctors are denying that the obesity epidemic—in which about two-thirds of Americans are overweight—is largely a result of sedentary lifestyles and poor diets. For the most part, weight control is a matter of balancing calories eaten and calories expended.

All bodies are not created equally, though. Calorie for calorie, some of us burn food for fuel more efficiently, and others pack on weight more easily. Even the same body through one's lifetime will process calories differently. We attribute this to a mysterious term call metabolism, the series of chemical interactions that turn food into energy.

Scientists have known for years that certain viruses can make lab animals fat. As with hormonal changes that can lead to weight gain, these viruses change the way the body processes food. Could it be that at least a small percentage of overweight people who eat reasonable diets are infected with some metabolism-changing virus?

The cold virus from hell

Magdalena Pasarica and Nikhil Dhurandhar of LSU presented their work on a virus called Adenovirus-36 last week in Boston at the annual American Chemical Society meeting. Adenovirus-36 is similar to common cold viruses and is known to cause eye infections in humans.

Back in 2000, Dhurandhar had shown that Adenovirus-36 can make chickens and certain rodents accumulate fat cells. Independent, follow-up work by others demonstrated that a similar virus called Adenovirus-37 did the same. In 2005 Dhurandhar was part of a team that found that 30 percent of a group of 500 obese patients had been exposed to Adenovirus-36, compared to only 11 percent in the normal-weight control group.

The new Pasarica-led study took the next logical step. She injected the virus in adult human stem cells, which had been removed with fat cells and other tissue during liposuction procedures and placed in a Petri dish. Nearly all of the stem cells exposed to the virus turned into fat cells, called adipocytes. Most of the uninfected stem cells, however, turned into bone and cartilage cells.

Although preliminary, these results do show for the first time that a virus can make the human body make more fat cells.

Stockholm not calling yet

Not all scientists are convinced that viruses contribute much, if anything, to the obesity epidemic, but Dhurandhar is not shaken by the ridicule. Somewhere in the back of his mind is the story of Australian scientists Barry Marshall and J. Robin Warren.

Marshall and Warren won the 2005 Nobel Prize for their discovery of a bacteria, called Helicobacter pylori, which now is known to cause up to 80 percent of gastric ulcers and 90 percent of duodenal ulcers. When they proposed this theory in 1982, they were laughed out of the room.

Everyone at the time assumed that ulcers were caused by stress and lifestyle. To prove his theory, Marshall swallowed a solution containing the virus and indeed caught a nasty bout of gastritis.

It would be unethical to inject humans with Adenovirus-36 and really not that fun. I'd rather get fat on tasty food, particularly some gumbo in Dhurandhar's and Pasarica's home state of Louisiana, one of the fattest states in America, where perhaps the virus runs free.

Christopher Wanjek is the author of the books “Bad Medicine” and “Food At Work.” Got a question about Bad Medicine? Email Wanjek. If it’s really bad, he just might answer it in a future column. Bad Medicine appears each Tuesday on LiveScience.