- Get weighed on dry land.
- Get weighed underwater, after breathing out all the air you can.*
- Do math.
Result? An approximation of how much of one’s body is fat and how much is muscle / bone (“lean body mass”). It’s considered more accurate than bioelectrical impedence or using calipers. There are now several mobile testing units scattered around the US that offer this at a low cost, often visiting gyms and/or company “Wellness Events” and “Health Fairs”. The hook, of course, is that you can find out how much of your body is fat and then focus on adjusting it “for optimum health”.
So why would I consider doing this? Curiosity, mostly. Partly because I’d done the biolectrical impedence at a gym a few years ago and wanted to compare. But mostly because I’ve generally found when I start working out regularly without dieting, a certain progression happens:
- Deal with muscle soreness.
- Gain 5-10lbs, possibly go up a bra size.
- Speed / strength begins to improve.
- Muscle soreness decreases; feel more alive, less enervated.
- Continue to improve speed / strength.
- Lose 10-15lbs, possibly go down a bra size or 2.
- Eventually reach a speed / strength plateau.
Generally this has driven relatives crazy.** I go to the gym but I’m not losing weight? I only lost a little and then stopped? How is this possible? If I’m getting stronger, aren’t my muscles getting bigger? Doesn’t muscle weigh more than fat? What is going on?
The question “Does it really matter that I’m not losing weight?” was not asked. (I suppose I should be glad that “But women shouldn’t add muscle!” didn’t come up. )
I do know, for some people, this sort of measurement lets them justify their weight to themselves or to a doctor or to an employer. An acquaintance in the Army was well over official Army weight, but because the caliper tests estimated his body fat was under a certain amount, he was given an automatic waiver. The idea being, of course, that it’s fat that’s bad, so if your weight isn’t due to fat, then it’s okay. In my case this isn’t relevent.
But still, I was curious. If I got tested now, would I get the same results in 6 months or a year? Or would I at least get a post out of it? ;)
So I did the test, which was also a trip into Fitness World, where fat is an enemy, working out is sacrament, and food is a tool to be used for the great god of Fitness. I’d gotten there early enough to know the tech was asking people if they had a personal trainer (he used to be a personal trainer) and that he was urging a diet book that “wasn’t really a diet, it’s a lifestyle change”. Many folks were being re-tested after several months; if they’d lost weight, the tech would congratulate them.
With me, the tech was friendly and welcoming when I asked if there was an upper limit to what his equipment could handle. I was pleased that his scale didn’t go “ERR”. The test itself wasn’t hard; I got into the tank/scale, tucked my toes under a railing that’s about an inch from the bottom, held the railing with my left hand and my nose with the right. Breathe out—all of it—and when he gets 2 identical readings in a row, we’re done.
(My first impression of the tank was that it looked like an immersion baptismal font. Again with the religious analogies.)
Naturally, this being Fitness World, I also played verbal judo with the tech. He asked me if I was working with a personal trainer; I said I’m following a program my physical therapist came up with after a knee injury. He asked if I knew how many calories I eat a day and didn’t seem too surprised when I said that the last time I tracked it, weighing and measuring, it was about 2000.*** (He said that was “a lot” .) He also asked if I’d had blood tests or a physical lately.
Me: Yes, that’s all fine.
Tech: Well, not really fine, right? (Implication: Prediabetes, high blood pressure, heart disease, and other Markers of Early Death Due To Lack Of Fitness)
Me: Actually, yes. They did find one problem—my B12 level was really low. I don’t absorb enough of it from food. It used to be called pernicious anemia, pernicious because it was always fatal. (Judo: Redirect from the Typical Fat Diseases to something weird.)
Tech: But they can treat that now…
Me: Yep. Right now, I’m lucky enough I don’t need shots, just lots of vitamins. (Get into water, busy with procedure.)
I did manage to grab my printout and leave, afterward, instead of having him explain the results to me. (I’d heard him explaining them to another new guy while I was waiting, and he didn’t say anything I hadn’t heard before.) And while I’m not entirely certain this is Absolutely Accurate, I did find it interesting.
For the curious:
| Body Fat: | 232.85lbs (57.8%) |
| Lean Body Mass: | 169.95lbs (42.2%) |
| Lean Body Mass BMI | 25.8 (overweight) |
This wasn’t too surprising, given that I do have lots of visible body fat and the bioelectrical impedence test I’d done about 5 years ago had me at 67% bodyfat. (I don’t think I’ve gained that much muscle since then—the methodologies are probably a big part of the difference.)
I do find it hilarious that, according to this test, I’m overweight without my fat. ;)
*In a lab, there’s a breathing apparatus to help figure out how much air is left in your lungs. This is to correct for the air in your lungs making you appear to have more bodyfat. The mobile unit just has you breathe out all you can.
**My reactions have varied depending on whether I was then in a dieting mindset or a fat-accepting mindset.
*** The last time I tracked calories I used a diet website which insisted I would lose weight eating between 2960 and 3310 calories per day. Meanwhile the tech’s printout says my “base metabolic rate” was calculated to be 2171 calories.
Living ~400lbs 
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