BOD PODs – What Are They?

aka How In-Shape Is The Jerd?

One of the most popular articles here at the Jerd is a piece entitled “How to Measure Your Body Fat Percentage.”

In it I detail why Body Mass Index (BMI) is a really poor way to measure your health (and why doctors need to stop relying on it), what body fat percentage is, and the five major ways you can accurately measure it.

Of course you should read that first, but here’s a recap of those methods (in order from least to most accurate) if you’re in a hurry:

• Body Fat Scales
• Body Fat Calipers
• DEXA Scanning
• Water displacement
• The BOD POD

One thing that has always bugged me about that article is that, at the time of writing, I had never done anything more accurate than using body fat calipers; and as frequent readers of the site know, I pride myself on being thorough with my research.

So when my gym announced they had a BOD POD coming in to do body scans I had to jump at the chance!

Out of the three higher-end methods the BOD POD was, not only the most accurate but also, the one that intrigued me the most; I think because, after a little Internet research, I was convinced it was fueled by some sort of dark sorcery instead of science.

So let’s take a look at exactly how the BOD POD works, and what my experience was like!

What Is This Bod Pod Thing Anyway?

Here’s what CosMed, the company that makes these crazy contraptions, has to say:

“The BOD POD Gold Standard Body Composition Tracking System is an air displacement plethysmograph which uses whole-body densitometry to determine body composition (fat and fat-free mass) in adults and children, and can accommodate a wide range of populations. A full test requires only about 5 minutes, and provides highly accurate, safe, comfortable, and fast test results.”

Sounds like sorcery, right?!?

They claim it is science though… In a nutshell, it tests your mass and density using air instead of water or calipers; and it does it surprisingly fast and accurately.

To within 1% actually, which is crazy!

If you’re interested in this supposed ‘science’, here’s how it works (but if you want to just believe my sorcery explanation, skip ahead):

The BOD POD is an Air Displacement Plethysmograph (say that three times fast!) that uses whole body densitometry to determine body composition (fat vs. lean mass). Similar in principle to underwater weighing, the BOD POD measures body mass (weight) and volume by sitting inside the unholy contraption unit.

Body density is then calculated using this formula: Density = Mass/Volume

Once the overall density of the body is determined, then body fat and lean body mass proportions are calculated. The BOD POD measures body volume, based on the physical relationship between air pressure and volume. This creates an environment where by directly measuring pressure it allows for solving an unknown volume.

First, the BOD POD measure the pressure response small volume changes by measuring the interior volume of the empty chamber, and then once again with the subject seated inside the BOD POD is also determined. By subtraction, the subject’s volume is obtained.

Example – If the interior air volume of the empty chamber is 400 liters, and volume of the chamber is reduced to 350 liters with the subject inside, then the body volume of the subject is 50 liters.

The BOD POD consists of two chambers, separated by an oscillating diaphragm. During data collection, the BOD POD door is sealed by a series of electromagnets and a gasket, and the diaphragm moves air back and forth between the two chambers. The pressure in each of the two chambers responds immediately to this volume change, and the magnitude of the pressure changes indicates the relative size of each of the chambers. During the body volume measurement, the subject breathes normally so the relevant measurement of lung volume for the BOD POD is not residual volume, but the average lung volume during normal breathing (average thoracic gas volume).

This information is then used to make corrections to the body volume measurement for obtaining final body composition measurement results.

Luckily, the technician didn’t try and explain this to me while I was there, because it probably would have twisted my brain a little.

What’s The Experience Like?

It’s extremely straight-forward, and a little anti-climactic, to be honest.

Other than not exercising 2 hours prior, or eating or drinking for an hour beforehand, you just roll up to the testing site for your appointment ready to go.

After the technician enters your pertinent data into the computer (height, weight, gender, age, etc…) you strip down to either a tight-fitting swimsuit or compression wear, toss on a skullcap, and take a seat inside the BOD POD for the initial measurements.

You go through 3 rounds, and each measurement takes about 30 seconds. You just need to sit relatively still, breathe normally, and listen to the gentle hum of the machine.

It’s completely painless; in fact, you can barely tell anything is happening.

The only thing that you might notice is possibly a little pressure in your ears, much like taking off in an airplane, during each measurement as the diaphragm pushes air into the chamber; but then again my ears are super sensitive, you might not notice anything at all.

#JerdProTip – Don’t take an overseas flight with a bad sinus infection, it will jack up your ears for life.

Also, in between each measurement session the technician opens the POD… so if you that easily get claustrophobic have no fear!

The whole thing took no more than 10 minutes, start to finish.

The Results Are In!

Bravo to those who get the reference… #NanooNanoo

Once it was all said and done, the technician gave me my results.

The bad news? I didn’t step out of that gizmo with super powers or looking like Captain America.

The good news? I am in pretty good shape!

So here are my numbers:

So what does all that mean?

It means that 17,921 other people have been tested by this unit, and therefore I should buy one and get in on this racket; but more importantly, it shows me weighing 163 lbs (like I said, Captain America I am not!) with 19.628 lbs of that being fat.

So 143.372 lbs of muscle, bones, organs and water.

This places me at 12% overall body fat percentage. Which, according to the chart, places me in the “lean” category.

So while not an “elite athlete”, I am doing pretty good for an IT professional who spends most of his days behind a keyboard and on mind-numbing conference calls.

The best part of this? I maintain this level of health by following the same advice I give right here on this site!

• I make my health a priority.
• I eat clean 80% of the time.
• I follow a basic strength training routine.
• I have active hobbies.
• I find fitness inspirations in the oddest places.

Of course genetics play a part in it, but I am 100% confident that all of you reading this can achieve similar results with a little willpower and a healthy dose of motivation.

You just need to apply these concepts over a long period of time!

There is one other thing worht mentioning though.

If you look at the bottom, it also breaks down a high-level estimate of the calories I should be eating to maintain my current weight.

I mentioned to the tech that I felt these were a little high, as when I go through the exercise to calculate for myself I come up with a Total Energy Expenditure of 2310 calories a day for the Active category. Not 2982.

That is a huge delta!

The tech admitted he wasn’t a fan of those numbers either, and that he often felt they were high as well. So if you do decide to give a BOD POD a whirl, I would take those numbers with a grain of salt.

The Verdict

I think it was definitely worth the $45!

Will I do it again anytime in the near future? Definitely not. And honestly, there is a good possibility I will never do it again… there probably isn’t a need.

But for a one time check-in? Totally worth it!

So much better than a personal trainer busting out the fat calipers and trying to get an accurate measurement if you ask me…

Of course I would like to see that body fat percentage a little lower, and the muscle mass a little higher, but overall I am extremely happy with the results.

What methods of body fat measurement have you tried? Have you had a BOD POD test?

Let me know in the comments below!

P.S. – Want to know more about BOD PODs? Check out www.befittest.com!

P.P.S. – Make sure to get your free e-book, “The 7 Fitness Obstacles Newbies Face” by subscribing to our newsletter… no spam, I promise!