T Nation

Underwater Body Fat Testing

Theres a company called getdunked that has a portable underwater body fat testing van that goes around to gyms and does tests. Has anyone has this done and how accurate are their results? Its $40 per test.

Hydrostatic weighing is the “gold standard” for body composition analysis. $40 seems kind of low to get this done. Research the company and see what you can dig up. If you find they’re credible, plug your nose and jump in. There’s no better way to find %BF, LBM.

I recently discussed a web site by that name in a thread about a week ago. As a company, it goes by a different name, but getdunked. is their web address. Personally, I think hydrostatic weighing is very reliable, but I have read posts on this forum that disagree, and I’m trying to keep an open mind. In our quite specific world of bodybuilding, in which we can measure our height and scale (land) weight, poundages, reps, tempo, duration of workout, calories, protein, body dimensions, etc., with untroubled accuracy, we still have to concede that all BF testing has some margin for error. As I’d mentioned before, I was once read in a dunk tank at 10.1 percent, and within an hour, a caliper test (at a franchise health club taken by a staff trainer) put me at 17.3. That one experience proves nothing, I know, except to explain why I’m skeptical of calipers. (For me, calipers are like a scale – cheap, fast, readily available. All that equals consistency, so the overall trends should be helpful even if the specific numbers are less than perfectly accurate.)

Regarding underwater weighing: when you get tested with this specific company, you lie in a tank, face down, across a plastic framework that’s attached to a scale above you. As the framework is lowered into the water, you expel as much air from your lungs as is humanly possible. Air is the enemy. In fact, it’s best to wear a tight-fitting bathing suit so no air gets trapped inside. Usually you go down about two or three times, and I assume the results are averaged. While you’re down there, you just hold your breath while the carriage system settles down and stops swinging, and you wait for the tech to tap you on the shoulder to come back up. It’s a little strange at first, but you get used to it surprisingly fast. My lowest reading was 6.0, and at that percentage, you sink like a rock.

Yes, it actually is forty dollars, and you can get three tests in a year for eighty dollars. To my knowledge, this specific company is only in Phoenix and Southern California. I’m sure there are some others. But enterprises like this do require an educated consumer. I’m curious to see to what extent these mobile units will catch on.