[tarice]

But once they diet to a point where they are not obese, the bacteria dies off?

I believe the theory is the reverse - by killing off the bacteria, the person becomes less obese.

Anti-biotics probably won't work as well as you hope because they kill all the bacteria in the gut - good and bad - which will just create more digestive problems.

[im3w1l]

Poop transplants. Sounds gross, but can apparently work.