By Mark Huffman

January 31, 2006
Heres another excuse for being overweight you might have a virus.

A study in the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, reports a human virus has been shown to cause chickens to get fat. Some scientists have concluded that finding suggests the virus could contribute to human obesity as well.

Another factor, scientists say, is how fast obesity is spreading through the worldwide human population. The only thing that spreads as fast, they say, is an infectious disease.

"The nearly simultaneous increase in the prevalence of obesity in most countries of the world is difficult to explain by changes in food intake and exercise alone, and suggests that adenoviruses could have contributed," the authors say.

Scientists involved in the study gave chickens three types of human virus. They found that the chickens with a virus called Ad-37 became obese, even though they were on the same diet as chickens that remained at a normal weight.

Another virus, Ad-36, has already been linked to obesity in other types of test animals. Blood samples from overweight humans show a strong likelihood of carrying the antibodies for the virus. The authors say more research might establish a stronger link between viruses and obesity.

While some might dismiss the idea that you can "catch obesity," the authors say an infection link might explain a lot. For example, doctors have long been perplexed by the prevalence of obesity in the third world countries, existing along side starvation.

Some 127 million American adults are considered overweight, with nearly half classified as clinically obese. The Centers for Disease Control puts the price of dealing with obesity at about $78 billion.