I dont understand. Your sons SCHOOL sent a note home saying that he was overweight?!?!?!?! I think that is hideous and not because Im fat, because how is his weight ANY issue of theirs?
I believe it's a local authority initiative that is designed to identify whether children, or rather their parents, have the information about how to ensure they supply a healthy diet to some degree. Obese children are far more likely to develop diabetes and other health issues, let alone the social problems they'll encounter when going to secondary school which is this year for my son's class.
They cannot force anybody to do anything but the parents of children that are identified as overweight to obese, are given information about portion sizes and food types that will improve their child's health. I have to say it taught me a thing or 2, like a portion should be roughly the size of your fist. Which is handy (no pun intended) as I have Hulk hands.
In all honesty there is a section of our society that don't give a damn about what experts say about nutrition, and feed their children on the same crap that they eat. This was highlighted when Jamie Oliver tried to overhaul our school dinner system and some mothers refused to acknowledge it and were filmed taking orders and handing out whatever the kids wanted to eat.
My daughter would eat nothing but chocolate given half a chance. Seriously.