The Guardian said:
Long courses of antibiotics may put babies and toddlers at higher risk of obesity when they grow up, according to US researchers.
Low doses of penicillin early in life can alter natural populations of gut microbes, which in turn may affect metabolism and lead to higher rates of obesity later in life, the scientists said.
The findings emerged from a series of experiments in mice, but build on earlier work that found children who had antibiotics before six months of age were more likely to be overweight as seven-year-olds.
Why are they surprised? That antibiotics fatten livestock was known to farmers for over half a century... and that the rest contained in the meat could be linked to a obese population was also supposed.