BMI Vs. Waist Circumference: Know How To Accurately Measure Your Health

For years, it's been all about BMI, but now experts are singing a different tune. Here's how to take in the changing information.

October 20, 2015
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For years, we’ve been trained to check out body mass index (BMI) whenever the scale goes up or down. You probably see this number scribbled on your medical chart when you go to the doctor for a physical (I do, anyway).

If you don’t, there are many handy-dandy calculators out there, so it’s not a shot in the dark for me to make this prediction: You are well aware of your “number.”

And that’s great. But as often happens, just as we’ve trained ourselves to be mindful of our BMIs, doctors and health experts have started touting waist circumference as a possible better measurement of overall health and disease risk. 

I know, I know. You just got used to BMI! Alas, the public health conversation is ever-changing–and confusing enough to cause a mind-plosion.

Does this mean you should forever let go of your BMI and start pulling out a tape measure? What’s the real difference between these two numbers? And why should you care? I’m here to break it down.

All About BMI

In case you’re not totally familiar with the concept of BMI or what it calculates, it’s been used for decades as a rough estimate of body fat based on your height and weight. Basically, it’s an educated, solidly predictable guess for most people–if you’re going to make an educated guess on a global scale, that is.

Historically, BMIs above the “normal” range are associated with higher disease risk–conditions like heart disease, hypertension, diabetes, and even certain cancers. Low BMIs are linked to conditions like infertility, anemia, and osteoporosis. So, it’s pretty important to keep your weight in the average range.

The drawback? It’s not perfect for all sets of people, because it’s based on just that: averages.

If you have a lot of muscle tone–you’re an athlete, you’re especially fit–it might appear you’re overweight because of your muscle mass. If you don’t have a lot of muscle tone–you’re elderly, you’ve been sick and lost it–BMI may undershoot your body fat.

All About Waist Circumference

Waist circumference encapsulates another idea about health that research is beginning to back up: It’s not how much you weigh, but the way you carry that weight. To get the lowdown on this trending (yet definitely verifiable) way to measure health, I asked physician and nutrition specialist Dr. Melina Jampolis to explain.

She says that visceral fat (or belly fat) is far more harmful than the fat that is simply found below the skin. This visceral fat tends to surround muscle and organs, which doesn’t exactly sound like a positive thing. “For women, you should maintain a waist size of 35 inches or less, and men should maintain a size of 40 inches or less,” Dr. Jampolis says. “Belly fat is very highly associated with disease risk.” That is, biggies like type 2 diabetes and heart disease. YIKES.

Although it’s not as convenient as BMI, properly measuring waist circumference isn’t that difficult. You can gauge yours by placing a tape measure around your middle, just above the hipbones. Breathe in, breathe out–and measure just after you release that breath.

What’s The Verdict, Man?

It’s worthwhile to know both measurements. BMI has the convenience and “good ol’ standby” factors–you can measure it at any time, basically, if you have access to a scale. But waist circumference seems to account for the many outliers that exist within the body mass index, like if you happen to be awesomely healthy and kill it in the workout room. (Go, you!)

So, I’ve hashed this out with Dr. Jampolis, and here’s my takeaway: Simpler is better. “Although there are limitations to the BMI measurement, as it does not account for bone density or frame size, it does give a range,” says Jampolis. “Aiming for a healthy BMI between 18.5 and 25 is a good goal.”

It’s a goal. But it’s a rough estimate. And at the end of the day, within reason, you’re aiming for the weight that makes you feel your best. Eat a healthy, balanced diet, and don’t freak out about numbers. There’s no one cookie-cutter weight you should be, and there’s no one definition of “healthy.” Homing in on one number, or a tiny ideal range that you hang onto for dear life, is going to lead to a lot of anxiety–which is not healthy.

If your numbers are getting out of hand, way above the healthy range, you should address your diet (of course). But otherwise, be mindful of numbers without getting too addicted to the tracking aspect. Remember your range, shoot for a middle-of-the-road BMI, live your life, and do the best you can. You’ll feel better that way.

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