In new study published this month, a research team claims to have found evidence that a contagious virus can contribute to obesity.

The team found that a specific human adenovirus Ad-37 seems to trigger obesity in chickens. Previous studies had linked other adenoviruses -- Ad-36 and Ad-5 -- to obesity in animals.

These and other adenoviruses cause colds and other common illnesses in people. There are about 50 of them, according to the team leader, Leah D. Whigham of the University of Wisconsin. Three have now been linked to obesity, and Whigham says the others need to be studied for similar effects.

"There is quite a bit of already published data with Ad-36 and its association with obesity," she said. "If you look at obese people, more of them have antibodies to Ad-36 than lean people."

The report is in the January issue of the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology - http://ajpregu.physiology.org

One of the long term objectives of researchers is to create a vaccine that would combat the effects of these viruses. This would, presumably, help people fight obesity.

**Traditional Causes of Obesity

Not surprisingly, other experts in the field of obesity are sceptical of the quest to pin the cause on viruses. According to the traditional view of obesity, its primary cause is quite simple. A person gains weight when he or she consumes more calories than they burn.

This involves two important factors -- diet and activity level. In countries like the U.S. where obesity has reached epidemic proportions, common diets are oozing with more fat and sugar than ever before. People are also generally less acitve and involved in sedentary activities such as sitting in front of computers all day, and in front TV screens all night.

**Some Facts about Obesity

Generally speaking, a person is considered "obese" when his or her health is endangered by the amount of fat stored in his or her body endangers. Here are some recent OECD statistics that show just how widespread the problem of obesity is:

Percentage of Population (+15 years old) who are obese

U.S.A. - 30.6%
Mexico - 24.2%
U.K. - 22.4%
Australia - 21.7%
New Zealand - 17%
Canada - 14.9%
Germany - 12.9%
France - 9.4%

That means, almost 1 in 3 Americans and about 1 in 5 Australians are so severely overweight that they have health problems because of their weight.

Obesity is now the most significant contributor to ill health worldwide.

Researchers and health officials have attributed a wide range of illneses to obesity. These include type 2 diabetes mellitus, hyperlipidemia, high blood pressure, heart disease, stroke, asthma, back and lower extremity weight-bearing degenerative problems, depression, and even certain types of cancer.

In the United State overweight and obesity have become an epidemic. Recent statistics show that approximately 127 million adults are overweight, 60 million are obese, and 9 million are severely obese.

This is a trend that has been accelerating at least since the 1970s. In just 24 years (1976 to 2000) the percentage of overweight adults in the U.S. went from 46% to 64.5%. And in just 12 years (1988 to 2000) the percentage of severely obese adults in the U.S. went from 2.9% to 4.7%.