Tuesday, March 9, 2010

Hydrostatic Body Fat Testing

I've been trying to get an accurate body fat assessment for a while now. I had mine tested last summer with calipers, but calipers tend to over-estimate body fat on people who've lost enough weight to have loose skin. (The loose skin throws the test off.) My fancy-dancy expensive scale tells me body fat %, muscle mass, hydration level, etc. but it seemed to me to read low. For example, it was telling me I had 10-12% body fat at a time when I clearly had more than essential body fat. My older, cheaper Tanita has always wildly overestimated body fat % -- it told me that mine was 70% at a time when it was closer to 55%.

I had a DEXA scan this Fall, but unfortunately, the machine PAMF uses doesn't do body fat. (Heck, they didn't even do a full body scan on my bones!)

So I was quite excited that Sports Basement's TriFest on Saturady included a company doing body fat testing with a dunk tank. This method, hydrostatic, used to be the Gold Standard before the DEXA scan came along so it's pretty darn accurate. And the best part is that they were only charging $20!

The test only took 15 minutes and I had no trouble getting the air out of my lungs (which I was worried about). The water was nice and warm too. Kind of like a jacuzzi without the bubbles.

The verdict: body fat % of 18.1. They also told me that, to get to my target body fat % of 15%, I'd have to weigh about what I weighed this past summer when I was guessing my body fat % was .... 15%!

Now I just have to figure out how to get back there while still building up my muscles. I want to add 3-5 lb. of muscle mass and lose 3-5 lb. of body fat, which would make me as small as I was this past summer, but at a slightly higher weight. My idea is that I'll be stronger and less scrawny, but the same size. I liked the size I was then but I didn't like how my ribs and spine were showing.

The interesting thing about my report is that they say my lean muscle mass is 95.6 while my scale says it's higher. That's probably why it says my body fat is in the 16-17% range instead of 18%.

My scale also estimates my BMR as around 1250 calories. This would make my daily calorie needs, not counting exercise, around 1530. The report from FitnessWave says that my daily calorie needs should be around 1750, but that's including exercise. My personal experience says that FitnessWave is wrong. My scale is closer because this summer I was losing with a net calorie average of 1550 a day and maintaining with a slightly higher net calorie range. But my average calories were well over 1750 and there is no way I'd maintain with that few calories. I wonder where those numbers came from.

I'm not sure why I care what my scale or some report says my calories should be. What matters is what happens in real life when I eat what I eat, not what some reports says. I think it's just part of my general need to be in control that I want some sort of rules to eat by instead of just going with the flow and seeing where that leads me weight-wise. Well, that, and I want to be lean enough to have a lot of good racing with great results, of course.

It's something I'm going to have to work on though. I'm hoping that this year goes a lot like last year because that will help me trust my body more.
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