Comments: I posted this because it is interesting, and lots of people now deal with this issue. In addition, perhaps the mechanism involves gut flora affecting brain structures governing reward or dopamine, stimulating the desire to overeat. Who knows?

Antibiotics that reduce gut bacteria linked to obesity
By Steve Connor, Science Editor
Tuesday, 3 May 2011

Scientists believe that the widespread use of antibiotics may be playing a significant role in exacerbating the obesity epidemic.