Not directly related to viruses, but here's a study that shows that gut bacteria from thin people will make mice thinner: http://www.nytimes.com/2013/09/06/hea

Not directly related to viruses, but here's a study that shows that gut bacteria from thin people will make mice thinner: http://www.nytimes.com/2013/09/06/health/gut-bacteria-from-thin-humans-can-slim-mice-down.html http://www.nytimes.com/2013/09/06/health/gut-bacteria-from-t... There are a lot of knobs that control metabolism, and scientists are only starting to figure it out.