The public schools in Medway, Mass., are early adopters of a trend that may well be coming to your public school system: Insisting students be weighed and that their body mass index (BMI) be calculated to determine if they are obese.

The results are sent home with them, like some kind of report card on their fitness level.

A 9-year-old girl named Shelby Sumner and her mother Lori-Ann raised concerns with the local Fox TV station in Boston about the policy.

This is a clear symptom of a public school system and state government in Massachusetts that has lost respect for personal boundaries and think of themselves as the rightful guardians of children, in place of their parents. Their program erodes the bonds between parents and children and shows no respect for the fact that pediatricians, not principals, should be monitoring their young patients’ health.

Calculating body mass index has nothing to do with teaching students history and English and math—things that public schools in Massachusetts would do well to focus on. It presumes—with no compelling rationale—that teachers are reliable trustees for health-related information, and that the public school system will offer reliable follow-up for those children deemed to be overweight or physically unfit.

The psychological impact on children of being told by their school systems that they need to lose weight is anything but clear. Children may well feel embarrassed or judged. They may wonder whether they will be watched in the future to make sure that they are eating less or complying with school/government expectations. They may fear that their classmates will ask them their “scores” (or find them out) and that they will be bullied because of their physiques. And these fears are justified.

The body mass index program in Massachusetts, and programs like it elsewhere in the country, could even set the stage for eating disorders in later life. The impact of “authority figures” compulsively monitoring a child’s diet and weight is not well understood.

Children may also (and here we may see the actual intention of the program) understand at some core, unconscious and unspoken level that the public schools and the state should have access to every corner of their existences and have a rightful claim on personal information of every kind. There is, after all, precious little difference between allowing the state to determine and record your body mass index and allowing them to stop by your home to see what you've got in the refrigerator. Just a few steps further down this flawed road of logic is the justification to sample your DNA to find out if you are prone to obesity or diabetes.

Here’s my advice to parents in Medway, Mass., and communities that have the same toxic idea: Turn the public school BMI program into a real teaching moment about free will. Tell your kids to refuse to be weighed and measured like herds of cattle. Tell them it’s your right and responsibility as families to stand up to authority when authority oversteps its boundaries. Tell them you’ll fight against any punishment that the school gives them, but that it’s worth doing the right thing, even if it’s uncomfortable and ends up costing them something. Tell them that the scales that matter are the scales of justice, and that the real measure of someone’s value in this world isn’t his or her body weight, but the weight of his or her ideas and ideals.

Dr. Keith Ablow is a psychiatry correspondent for Fox News Channel and a New York Times bestselling author. His book, “Living the Truth: Transform Your Life Through the Power of Insight and Honesty” has launched a new self-help movement including www.livingthetruth.com. Dr. Ablow can be reached at info@keithablow.com.