Measuring Obesity

Mar 29, 2013

Visit the doctor and someone will almost certainly take your temperature, blood pressure and weight. All it takes is a thermometer, arm cuff and a scale.

Patients have a pretty good idea what the readings mean. ”101” - You’ve got a fever. But the tools to measure fat are much more diverse - and each has its drawbacks. Reporter Anne Glausser from member station WCPN explores three ways to measure fat.

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First, let’s dispose of a common misconception: “To measure fat…just jump on a scale.”

Seems logical; it’s what everyone talks about when discussing obesity but a scale is a primary tool to measure …well, weight.

It’s precise as far as it goes - weight is an indicator of health - but it doesn’t shed much light on how much fat you’re carrying around, along with bone, muscle, organs and other body content.

SHAFFER:  Your weight tells you nothing.  Your weight tells you nothing.

That’s Gina Shaffer - a personal trainer in Elyria.

SHAFFER:  You have to find out what you’re composed of. When you find that out, then you know where to go, then you know what’s happening to you, then you know how you are succeeding.

Doctors couldn’t agree more.

The most common fat measurement they use is low tech--It’s called the Body Mass Index.

You’ve probably heard of it but not a lot of people can rattle off their BMI number.

MetroHealth’s Dr. Eileen Seeholzer says that’s changing.

At her clinic, everyone goes home with a sheet in hand about their B-M-I.

SEEHOLZER:  Body Mass Index is basically a ratio of two measurements:  a person’s height and their weight.  It gives you a—the BMI gives you—a common number.

That’s weight divided by height, squared.

There are lots of easy-to-use calculators online to get your personal number.

A BMI of over 25 is considered overweight; 30 and above is obese.

High BMIs are a red flag for health problems like diabetes and heart disease.

But the BMI doesn’t directly measure the fat in your body; it’s just an estimate.

It doesn’t breakdown your body composition.

SEEHOLZER: That’s why they call it a screen; this isn’t a lab measurement.

The second fat measurer in our little tour is …a gadget.  One you might find in a health club or gym.

Let’s go back to Gina Shaffer, the personal trainer.

(Nat sound of gym fades in)

SHAFFER: Alright, so take your shoes and socks off.

Shaffer is working with Julie Rush from Avon Lake and she’s about to step on a scale at the gym in the EMH Elyria Medical Center.

The first thing on Schaffer’s agenda is to get some measurements.

SHAFFER:  Let me just program this in…and how old are you? RUSH: 55…And how tall? RUSH: 5’ 8”.  And go ahead and hop on.

This isn’t your typical scale.

It’s a “bioelectrical impedance” machine.

It sends an imperceptible, safe electric current through the body.

The current passes through lean body mass faster than when it encounters fat.

By measuring this resistance, the machine computes the amount of fat in the body.

SHAFFER:  Ok, so let’s look at your numbers.

Rush gained 5 pounds since the last check in and she’s a little disappointed. But Shaffer says that’s not the thing to focus on:

SHAFFER:  Look at your body fat:  your body fat was at 51.8 and now you’re at 51.5, so you lost a little bit of body fat…Then right here you got—see you’re up like three pounds muscle.  RUSH:  Hmm. SHAFFER:  That’s good, that’s good. RUSH: OK.

There are many other ways to get at a body’s fat content.

Calipers – those tong-things a doctor pinches your skin with; an underwater measuring tank.

Some can seem a little weird.

THOMAS:  We call this the egg.

(Sound of Bod-Pod opening)

Alicia Thomas runs studies at a MetroHealth research lab.

She shows me what’s called the Bod-Pod.

THOMAS:  It smells like a boat—it’s made of fiberglass. It has a nice seat in here for the patient…

The Bod-Pod is a high tech way to precisely measure body fat.

It’s used in research, and health spas and clinics.

Thomas says it’s quick and safe.

THOMAS:  The worst part is that you have to put a bathing suit on.

I climb inside to see what it’s like.

Then they close the hatch.

(Sounds of bod-pod closing and sounds inside bod pod—little pops and puffs)

It blows puffs of air at you.

It measures fat through changes in air pressure.

It’s accurate and expensive.

Kinda fun—but is it necessary?

SEEHOLZER:  I don’t think I could ever say one needs a bod-pod (laughs).

That’s Dr. Eileen Seeholzer again.

She says the main thing is to keep track of your measurements – no matter which method is used.

Those who do tend to make more progress with their health goals.