While I think an very large number of kids, and adults as well, are doing a huge dis-service to themselves that will either make them very sick down the road or kill them by gaining so much weight (and as a nation we are headed for a very sick population), I think doing a letter is in such poor taste. She should just turn off her lights. I see some tricks coming her way.
We kind of struggle each year with handing out candy due to all the pounds of sugar that get consumed but choose to hand out the smaller snack size candy (although I have put together a ziplock with usually five pieces of different candy, so not sure it makes a difference). I try not to make it all chocolate, and switch up kinds of candy but honestly it really is still pretty much sugar. I hated getting apples as a kid so don't want to go that route. The fruit gummy candies we gave out one year still have a lot of carbohydrates and dentists say they are worse for you since they stick to your gumline until you brush well. I have also altered handing out less candy and adding glow bracelets which surprisingly go over well. Of course I wonder what happens to all those glow bracelets after they stop doing them chemical thing and become a disposal isssue that really didn't need to happen.
Tough choices for those handing out candy and trying to be responsible on one level or another. The letter and singling out those overweight kids is really a bad choice. I'm still shaking my head over hearing this.