SOUTHERN CALIFORNIA -- Southern California schools have started sending letters to parents saying that their kids are overweight.

Letters like these are also said to be going out at schools across the state, including some schools in Sacramento.

So-called "fat letters" are the opening salvo in a fight to end childhood obesity. At least 19 states are sending letters like these to parents. 

According to a dietician at a school in the San Fernando Valley, obesity is determined with weight charts matching age, size and weight.

Parents are then sent "healthy" or "unhealthy" letters.