Federal regulations require pediatricians to calculate your child's body mass index-that's their proportion of height and weight.
Dr. Heather Christianson at Complete Children's Health tells me the measurement isn't perfect, but it's a way to start an important conversation with families.
"It doesn't take into account body fat percentage. That's a hard thing to measure in a busy practice. However, for the majority of people body mass index allows us to look for trends," said Christianson.
Christianson has practiced for 14 years. She's noticed BMI becoming more important in recent years.
"I know I didn't spend as much time 14 years ago. But, we've seen this problem grow in our country. It's become an important part of each and every well visit that we review what a child's taking into their body and what they do to expend energy," she said.
Looking at BMI starts at age two at Complete Children's Health. It may seem young, but Christianson uses it to start a more important conversation with families.
"That's a great time to sit down and talk about some simple changes that can be made at home. Not only to help the child, but the entire family," she said.
And to help kids understand that weight is about their health, not their image.
"God gave them the body they have. That's the way it is. Might be shorter than they want to be, might be taller than they want to be, or maybe bigger boned than they'd like to be. But it is what it is, you have to put your arms around that and let it be and move on. But with that body we want it to be as healthy as possible," said Christanson.
It's a tough conversation to have - to tell a child they are overweight.
"I have teenage girls who sometimes don't like to see their growth chart," she said.
But, in Christianson's experience, it's worth the effort. And not more effort than any family can handle.
"A plan for how to manage the obesity or overweight situation is very different depending on the situation, and it has to be taken slow and within the limits of the family's budget and time," she said.
If you have questions about BMI, ask your child's doctor.