New evidence shows that America's obesity epidemic may be connected to our high consumption of [antibiotics]. Investigators are beginning to piece together a story about how gut bacteria shapes each life, beginning at birth, when infants are anointed with populations from their mothers' microbiomes. Babies who are born by cesarean and never make that trip through the birth canal apparently never receive some key bugs from their mothers - possibly including those that help to maintain a healthy body weight. Children born by C-section are more likely to be obese in later life. Scientists are racing to take a census of the bugs in the human gut and - even more difficult - to figure out what effects they have on us. What if we could identify which species minimize the risk of diabetes, or confer protection against obesity? And what if we could figure out how to protect these crucial bacteria from antibiotics, or replace them after they're killed off? The results could represent an entirely new pharmacopoeia, drugs beyond our wildest dreams: Think of them as anti-antibiotics." While researchers work to unravel the connections between antibiotics and weight gain, they should also put their minds toward reducing the unnecessary use of antibiotics. One way to do that would be to provide patients with affordable tests that give immediate feedback about what kind of infection has taken hold in their body. Such tools, like a new kind of blood test, are now in development and could help to eliminate the "just in case" prescribing of antibiotics.