Bacteria inside our guts will determine our feature to be "obese" or "lean". Researchers in Washington University, U.S.A., have transmitted human's gut bacteria into mice and found that mice with bacteria from obese person are increasing weight.
Researchers started by finding four pairs of human twins, where one twin was obese and one was lean, and then implanted a sample of each of the twins’ gut bacteria into mice that were raised in sterile conditions. Even though all mice were fed the same exact diet, the mice populated by bacteria from the obese twin grew fatter than mice who got the microbes from the lean twin and their metabolism changed, too.
Another stage of the experiment led to an even more interesting result: Combined with a healthy diet, “lean” microbial communities can be transmissible.
Remarkably, when the obese and lean mice were later put in the same cage for 10 days, the obese mice began to show the same “leaner” metabolic profiles of their cagemates (through feces, mice exchange bacteria when they share a cage, but the researchers wanted to find out which bacteria would dominate). This transformation only happened when those mice were fed with healthy diet. Transformation didn't occur when fed with low fiber and high saturated fat diet.
The results emphasize that "lean" gut bacteria combining with healthy diet could help to control obesity. Today, more and more people are taking "good-bacteria" (probiotics) to improve their health. Will a "health-lean" bacteria be added to the line of probiotics one day? So far the study was only done with mice and the same interactions may not happen in humans--but the results offer hope.