A new study, presented at the American College of Cardiology's annual meeting, has found that more than one in three middle school students who regularly eat school lunches are obese or overweight. Does that mean parents should stop their kids from buying lunch at school?  Not necessarily, according to Michael Barrett, a cardiologist at Temple's School of Medicine. "There's no way to be sure what you’re packing in their lunches is what they are actually eating; foods can be traded and snacks can be bought from vending machines or local stores," he says.