Possible Virus X....?

A friend of mine who read my last post has asked, could our "Virus X" be an obesity bug? And if so, might we already be suffering an epidemic?

Indeed, some research suggests that both viruses and bacteria could play a role in weight control:

• A recent study in Nature (there's also a related news story in JAMA) found that the balance of two divisions of beneficial gut bacteria, Bacteroidetes and Firmicutes, seems to be important in determining an individual's propensity for obesity.
• Nikhil Dhurandhar, a researcher at the Pennington Biomedical Research Center in Louisiana, and Richard Atkinson, a pathologist at Virginia Commonwealth University, are studying the link between human adenovirus AD-36 and obesity (they co-founded the obesity research company Obetech). Dhurandar found that AD-36 causes obesity in chickens and rats, and that some obese people also carry this virus. (He coined the term "infectobesity.")
• Another study (co-authored by Atkinson) has found that AD-37, an adenovirus closely related to AD-36, also causes weight gain in chickens.

If the cure for obesity is as simple as immunization against a group of adenoviruses, well, I'll eat my running shoes. In all seriousness, though, the idea that microbes could play a role in weight control is not actually that surprising to me—I recently read a fascinating book that makes me think that perhaps infections play a role in more things than we realize.