Bacteria in intestines play role key role in weight gain, study finds

"When the researchers transferred bacteria from obese mice into so-called gnotobiotic mice, which were raised in a sterile environment and had no bacteria in their guts, the mice gained more weight than did those receiving a similar amount of bacteria from lean mice, even though they were fed the same diet. "

http://www.latimes.com/news/nation-and-world/la-na-weight-gain12-2009nov12,0,5760388.story?track=rss