Hydrostatic Body Fat Testing and a Shift in Focus

A few weeks ago, while watching Extreme Makeover: Weight Loss Edition, the bright idea of having my body composition scientifically measured popped into my head. My friend Google and I discussed my options, and as luck would have it, a mobile hydrostatic testing station was coming to the gym just a few blocks down the street. Short of an autopsy, water testing is considered the “Gold Standard” of body fat testing and is one of the most accurate ways to measure percentage. I was prepared to drive all over LA to find a water tank, but instead the water tank was gonna drive to me! How lucky did I get?! I’m not a member of the gym, but testing was open to everyone so I reserved my spot for 6pm after work. Yesterday was the big day. It may have come 14 months too late, but in this case, better late than never.

A few hours before my test, I started to get nervous. Not about learning my fat percentage, but about going near a gym with hardbodied men and women looking me over and judging me. Yes, even after over 120 pounds lost, I still feel that same anxiety about gyms. And I wasn’t even going there to work out! I started to get restless at work waiting for my appointment, and nearly thought about canceling, so I went way early to get it over with; to rip off the bandage.

When I walked into the small, intimate gym, an employee immediately greeted me at the door and asked how he could help me. My nerves were put at ease, and I told him I was there for testing. Since I was way early, there were a couple people ahead of me so he told me to just hang out, check out the equipment, and it would be my turn before I knew it.

The Lab
I really wasn’t sure what to expect, so it comes as no surprise that I did not arrive fully prepared for my test. I didn’t bring a towel, I didn’t have a hair tie, and I came straight from work so I only had the shoes on my feet, which happened to be a pair of fuck me heels. At least I did bring my bathing suit, but since the mobile lab was outside, I couldn’t go barefoot. There I was, standing around in a bathing suit and heels like some kinda beauty pageant reject. Shortly after I was due up, kicked off my heels, and took a seat in the big water tank while the technician explained the proper way to attempt to drown myself. (Photo credit: Body Fat Test)

If you are not familiar with hydrostatic testing, I’ll try to sum it up in a few sentences: fat floats, and muscle (or more accurately, “lean body mass”) sinks. When your fat ass dunks in the tank, the amount of water displaced gets measured, which tells you how much of you is adipose tissue (fat) and how much of you is everything else (muscle, bones, organs, etc.). Check out Body Fat Test for a more detailed explanation.

The Test
When you are about to submerge yourself in water, what do you normally do? Inhale the deepest breath of air, plug your nose, and dive. But in this case, air is not our friend. Air = fat, and nobody wants that on their test. I had to exhale and release as much air as possible from my lungs, plug my nose, and slowly lie back until I was under water. I’ll admit, on the first dunk, I sorta panicked. I got in the water way too fast and didn’t relax while I was under. (Photo credit: Body Fat Test)

The second and third dunks were better, but that first second after you’re submerged and the water silences the world around you… it’s fucking terrifying. After that passes, your body calms down a bit and you realize you could probably stay under there for a minute if you had to. Luckily the technician taps you out after about 5-7 seconds.

The Results
Ah, FINALLY! The shit you’d been probably waiting for.

Age: 30
Height: 5’0″ (WHAT! I always thought I was 5’1″. Devastating.)
Dry Weight: 162 pounds (Hey, it was late in the day…)

Weight of Body Fat:
 49 pounds
Weight of Lean Body Mass: 113 pounds
Body Fat:
Lean Body Mass: 69.75%

The Analysis

Obesity, or excessive body fat, is generally defined as a value greater than 32%. However, the detrimental health value of obesity does have a relationship to your age. It is far more severe to be at or above 30% at 50 years old than it is at 20 years old. Your calculated percent of body fat of 30.2% at a weight of 162 pounds is below that level.

I nearly forgot to mention another very important piece of data measured by this test, that I should have known from day one…

Resting Metabolic Rate
Resting metabolic rate accounts for approximately 70% of daily energy expenditure. It is the amount of energy needed to sustain the body at a minimal resting level. This rate varies between individuals, but according to your body size and body composition, you have a resting metabolic rate of 1612 calories per day.

My Thoughts (because there weren’t enough above)
My results were about what I expected, and while 30.2% puts me in the “poor” range, I learned that there was so much more to this number than I had initially thought. First, though my BMI still technically calls me obese, my body fat percentage doesn’t. And that makes me so happy I can’t even tell you. Sure, I just barely squeaked by, but still, I’m not obese mothafuckas!

Second-of-ly, wow, I have been eating way too little. It is extremely difficult for me to wrap my head around the idea that when I’m simply sitting on my ass doing nothing, I should still consume 1612 calories per day. Of course if I ate less, I would lose more weight, but that weight would be fat AND lean body mass. There’s no way around losing a little bit of muscle with fat (well not any methods that I’d be able to sustain, anyway), but I will certainly do my best to keep it to a minimum.

And lastly, thanks to this test, I am finally ready to completely let go of the number on the scale. I am no longer yearning for big numbers each weigh-in, and I finally get why losing more than one to one and a half pounds per week is not always a good thing. Deep down I always knew this to some degree, but it is clear to me now that your body weight does not necessarily reflect how your body looks. Take this comparison chart (found via Google, linked to source) for example. We are to assume all three women weigh the same, but their body fat percentage makes a huge difference. (Disclaimer: I don’t know these women nor do I know their actual stats, so they might not weigh the same, but you get the idea, right?)

The point I am trying to make is that I am no longer working towards a “goal weight” but a “goal body fat percentage.” Whatever the number on the scale says when I’m at my goal body fat percentage is secondary. So what’s that goal? I’m not trying to be a super lean and cut up athlete here. I just want to be a normal, healthy, fitness-y 20-21%.

Not-So-Scientific Comparison Test
I’m truly bummed that I don’t have a starting test to compare my results to (AGAIN, IF YOU’RE JUST STARTING OUT – TAKE THE DAMN TEST NOW!) but I was tested via handheld machine at my old clinic a few times. I called them this morning to get that data, which could have been awkward since I just kinda stopped showing up a year ago, but they faxed it over at my request without hesitation. It’s a shame that I don’t really jive with their program because I do enjoy the people who work there. Anyway, my readout had three stat lines: one from when I first started a diet with them back in 2006, a progress update after having lost 70 pounds in 2007, and a reboot update after I gained it all back and restarted the program in May of 2011. If I put all the stats together, they look like this:

Fat (lbs)
Lean (lbs)
Fat (%)
Lean (%)

I crunched some numbers and during my first stint at weight loss, I was losing body fat at an approximate rate of 0.86% per month. My workout regimen was sorry ass shit back then: a few days a week at Curves and 30-minute brisk walks around the neighborhood. This time around, you know all about my workouts, and I’m considerably more toned and buff (heh heh) than I was before. (Side note: I saw pictures I took when I was previously at ~200lbs and thought, no fucking way, I didn’t look that fat at 200lbs this time! Muscle baby.) Right now I am losing body fat at an approximate rate of 1.22% per month. I’ve read a few different places that between 1-2% per month is a healthy average.

Whew! That was a lot to think about, write, research and compile, and a lot to read too. But I hope you made it all the way down here and found this post even a little bit helpful. To sum it up in a couple sentences:

1. Don’t only focus on shedding pounds; shed that FAT!

9 thoughts on “Hydrostatic Body Fat Testing and a Shift in Focus

  1. July 24, 2012 at 12:06 AM

    I may have to borrow your friend google but I am not sure if I have the balls to get in a bathing suit right now. Very interesting info though.

  2. Estella
    July 24, 2012 at 12:07 PM

    Maaaeee! You’re killing it girl, even though I’ve been silent as hell on twitter, im still reading ur blog and ur amazing, keep it up!

  3. August 2, 2012 at 4:33 AM

    I dont know how to swim and I have a fear of putting my head under water, so i couldn’t do that test. I did do a Body Pod test in the exercise and wellness department at my school a couple years ago. I wish I would have kept the info. I would really love to know my BMR and what the proper amount of calories I should be eating each day is.

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