Now, I know that childhood obesity is a big problem in this country but let me open up your eyes to something- kids are not fat because they get to eat treats sometimes. Kids are fat because they eat too much food all of the time. Kids are also fat because they sit around playing video games and watching television while eating said treats.
What is the solution? It starts at home. Feed your kids normal food and practice portion control. Stop giving them Gatorade, soda and juice when they are thirsty- believe me, if they are thirsty enough they will drink water even if they hate it. Be a parent and just say no if your kid wants something that you don't want them having. If they are whining because they want a Happy Meal and they've already had a Happy Meal this week look them in the eyes and say heck-to-the-no.
So for God's sake, let the kids bring in a treat on their birthday. It doesn't even have to be cupcakes- my son's old nursery school let you bring in snacks like crackers, pudding, fruit, Hoodsie Cups, etc. and it was fun for the kids.
This just goes to show that people just completely bark up the wrong tree about these kind of things- schools have too much to do to have to worry about why your child is fat, that is your job. My kids aren't fat so I get to focus on why my lax parenting has turned them into little monsters...