Researchers at the University of Wisconsin are finding that viruses — specifically certain human adenoviruses — may actually be causing some cases of obesity. Adenoviruses are usually associated with common infections like colds and pink eye. They can also cause enteritis and diarrhea. But as nutritional scientist Leah Whigham says, "Those are the acute responses. We're e finding that some of these viruses also cause a more chronic response that involves increased fatness.
It would be unethical to test the suspected viruses in humans, so for now all of the evidence for their effect on people comes from associative data. Previous work done shows that in a randomly tested population, 30 percent of obese people had been exposed to one of the suspected viruses as compared to only five percent of lean people.