A Question From the Edge: Is Fat Contagious?

The idea that a virus might be partly responsible for weight gain "is sort of a fringe idea as opposed to a cutting-edge idea," Heymsfield said. "But Doctors Atkinson and Dhurandhar have done their homework. There's nothing to suggest that their observations are not valid to this point."

As Heymsfield noted, "they've gone from animals, looked at humans, found associations, and are now shoring up their work with populations. That's the usual and important thing to do."

If all goes as planned, Atkinson's new company -- Obetech, based in that biotech park in Richmond -- will begin offering the first lab blood test for AD 36 in September. The test is expected to cost about $125 to $150. It will take two to four weeks for a patient's results to be ready.

Atkinson's plan is to look for the virus not just in patients referred by physicians but also in large populations. He's been approached both by West Virginia state health officials and by the Air Force to test blood collections for the virus and compare findings with weight records for those populations.

If the link between obesity and AD 36 "pans out, it would be very powerful evidence that the virus is contributing to the problem of obesity, and that might help change a lot of things," Atkinson said. Chief among them: proving that obesity is a disease, not just a marker for lack of willpower. "What we hope is that if we can demonstrate that the virus is causing obesity, it will be more difficult for Medicare and health insurance companies to deny treatment to these people." [Recent changes in Medicare may soon make it easier for obese people to receive some coverage for weight control treatment.]

Those who know they are infected with the fat virus could also take additional steps to avoid weight gain, although researchers don't expect that it will necessarily lead to ground-breaking treatment.

"Having the fat virus doesn't guarantee that a person will become obese," Atkinson said. "But we know that a high percentage of animals infected with the virus became obese. It will alert people that they are going to have to be more careful than the average person to prevent weight gain. At least that is what we think."

Exactly how AD 36 may promote weight gain is still not understood. Infection with the virus "does not appear to cause very severe illness," Atkinson said, so people aren't likely to know they've had it unless they get tested.

One theory is that infection prompts fat cells to pull more triglyercides and cholesterol from the blood -- an idea that fits with the lower levels of these substances in the blood of those who have had the virus.

Other research points to the possibility that infection may significantly reduce the amount of leptin produced by fat cells. And still more studies suggest that AD 36 may prompt fat cells to mature more quickly and start storing fat.

"It's really not clear what may be going on," Atkinson said.

Still: a fat virus?

"If you told people 20 years ago that ulcers are caused by a bacterial infection, you would have been laughed at," Heymsfield noted. "But it turns out that ulcers are caused by infectious disease. So we scientists have learned to have open minds."

And so should you. But in the meantime, if you'd like to control your weight, eat less and move more.•

Share Your Tips or ask questions about healthy nutrition and activity when Sally Squires hosts the Lean Plate Club online chat, from 1 p.m. to 2 p.m. today, on www.washingtonpost.com. Can't join live? E-mail leanplateclub@washpost.com anytime.

New To The Club? The Lean Plate Club is devoted to healthy eating and boosting activity. To learn more, and subscribe to our free e-newsletter, visit www.washingtonpost.com/leanplateclub.