Is BMI meaningless, especially for kids?

I was quoted this morning in a piece on ABCNews.com about tracking kids’ health through the use of BMI. An adult’s BMI is calculated using height and weight, and that number puts you in the underweight, normal, overweight, or obese category. It doesn’t take into account muscle mass, cholesterol, blood pressure, sugar levels, activity levels, waist size, or any other indicator of health and fitness.

And when you start talking about BMI for kids, it gets more complicated, because a BMI that’s considered OK for a ten-year-old is obese for a seven-year-old. I don’t think using BMI to track kids’ health is a good idea at all. (However, unlike most of the commenters on the ABC piece, I don’t think trying to improve kids’ health is a commie-liberal-big brother idea either – those commenters get paranoid and nutty pretty fast.)

Whether a kid is healthy or not is complicated. My son was in the top 5% on the BMI charts for a seven-year-old when he was seven, which is what triggered the note home. The problem is that the kids’ charts compare kids by age. My son was towering over the other kids in his class, so the comparison was completely out of whack. The charts allow for the fact the older kids are supposed to have a higher BMI, but not for kids who are very tall for their age.

It’s just one of those things where a number or a label without information is useless. I knew the assessment was ridiculous, but had to actually look up the info and explain the BMI-by-age concept to my husband to talk him down after he saw the letter. He’s not a stupid guy. He’s actually quite smart, smarter than me in many ways. But the government told him his son was obese and he took them at their word. That’s a problem on many levels.

What’s the answer? I have no clue. I’m lucky that I have one kid who chooses to eat like a health nut and another who is active enough that he burns off the huge amount of carbs that he consumes. If one of them had a health problem I would expect my doctor to talk to me about it. He’s got all of my kids’ information right there in front of him, and even more important, he’s got my kids right in front of him.

Does he need the government’s guidance when talking to me about my kids’ weights? I don’t think so, but if they’re going to tell him anything, I’d rather it be something useful, like whether or not my kids can run and play with their classmates and how they do on fitness tests. What their blood tests should look like. And yes, whether their measurements are in a safe range, based on many factors. Using one number to target kids will include kids who don’t need the intervention and exclude kids who actually need the help.