Are Antibiotics Making Us Fat? Scientists hypothesize that killing stomach bacteria is a bad thing By Kevin Spak, Newser Staff Posted Aug 23, 2012 1:02 PM CDT 19 comments Comments Antibiotics might make you better, but they also might make you fatter. (Shutterstock) (Newser) – Antibiotics may make you get well, but are they also making you get fat? Some microbiologists think they might be, by killing off gut bacteria that would otherwise help digest food, Wired reports. In a study published this week, NYU researchers found that infants exposed to antibiotics before they were six months old consistently added more body mass years later. "Early-life antibiotics are changing the microbiome … at a critical time in development," explains co-author Martin Blaser. Farmers have been giving cows antibiotics for years after observing that it helped to fatten them up, and another Blaser study, published yesterday, found that mice given antibiotics saw their body fat percentage shoot up 15%. Of course, those animals received constant streams of bacteria killers, not the quick bursts humans receive. Blaser says he's moving to study quick-burst effects now, but adds that humans might be getting a steady stream of antibiotics too—through the meat they eat.