Tuesday, December 28, 2010

DEXA Body Fat Scan

We all know that BMI (Body Mass Index) is altogether unreliable as an indicator of health. It's junk science, and it doesn't tell us anything about body composition. There are plenty of better ways to measure body composition, and in Tim Ferriss' "The 4-Hour Body," he discusses a bunch of 'em -- some of which are much less accurate than others. Calipers and measuring tape only get you so far. And do you accept as gospel truth what the bio-electrical impedance bodyfat scale in your bathroom tells you? 'Cause you shouldn't.

Ferriss examined nine different methods of body composition testing, and "[a]fter dozens of trials with multiple subjects, and taking into account both constancy and convenience (including cost), there were three clear winners." The first of the three: DEXA (dual energy X-ray absorptiometry) -- the "gold standard" of body composition testing. DEXA is a full-body scan typically used to measure bone density, but it's also capable of pinpointing body fat percentage and location. In a nutshell, you plop down on a table, fully-clothed, and a movable electronic scanner X-rays your body from head to toe. It takes less than ten minutes, and you get a keepsake photo of your lumpy silhouette (think airport security pornoscan shots) showing all the fleshy parts you'd prefer to conceal with Spanx and oversized football jerseys. Fun!

Bonus: The unassuming little medical office where Ferriss gets his DEXA scans is just a few freeway exits from my home.

So for kicks, both M and I decided to give this DEXA thing a shot. This afternoon, after shelling out $65 and filling out some simple paperwork, I found myself lying on some crinkly paper, staring at the ceiling while a softly-whirring mechanical arm performed low-dose X-ray scans of my body. It took no time at all. Before I left, the friendly technician spent a few minutes going over my DEXA measurements with me.

Check me out. (Nice lungs, right?)

I'd gained about ten pounds over the past six months, so I figured my body fat percentage had gone up, too. But I'm happy (and more than a little shocked) that my low body fat level puts me in the 1st percentile for my age, meaning I'm leaner than 99 percent of other men in their mid-thirties.

Despite switching to a Paleo diet and adopting a 3-days-a-week CrossFit schedule (i.e., eating loads of saturated fat and exercising less frequently), I've maintained a sub-10 percent body fat percentage. The weight gain, it seems, is largely muscle.

I don't know if it's due to eating Paleo, lifting heavy stuff and doing short metcons a few times a week, intermittent fasting, or a combination of the above, but something seems to be working.