If you're fighting the battle of the bulge, most of your attention — and frustration — is probably aimed at your midsection. It makes sense, since that's where the extra pounds tend to gravitate, especially with the creep of middle age, piling on to form that dreaded spare tire.

But a growing body of research suggests there's another, less visible reason to focus on your gut if you want to lose weight. Scientists led by Andrew Gewirtz at Emory University reveal that your intestines harbor a universe of bacteria — the so-called gut microbiota — that may play an important role in whether your body will store the food you eat as extra pounds.