This is an interesting piece about abnormal immune systems in mice from Emory University in USAToday. The researchers noticed that with inflammation and weight issues they saw abnormal intestinal bacteria. Essentially realizing that the unhealthy bacteria made the mice eat more.

The researcher Gewirtz, transferred bacteria from the fat mice directly into the germ-free intestines of normal newborn mice — and those mice began eating more and developed inflammation and insulin problems.

“People are getting obese because they’re eating more, but it suggests the reason they’re eating more may not simply be that calories are cheap and available,” Gewirtz said. “The reason they’re eating more may be an increased appetite resulting from changes in intestinal bacteria.”