I have one of the "fancy" Bowflex scales that computes BMI and measures water, muscle, bone and body fat percentages as a function of height, weight, age, sex and activity level.
As I started P90X, I setup the scale per the instructions and given my activity level of BJJ, set it to 4 (moderately active,) and the "normal" setting as opposed to "athlete." Given where I was when I started, I was 175 pounds and almost 21% body fat. Seemed reasonable and accurate.
As I progressed through the last two months of P90X, the fat disappeared but even though the muscle weight increased, the BF reading did not decrease very much at all (down from 20.6% to 16.7%) which, given even an eyeball measure didn't seem possible let alone accurate.
@PowerGeek experienced something very similar.
So I did what he did and purchased a body fat caliper set from Accu-Measure which you can pick up online or at GNC:
...taking the measurements, it consistently has reported that I am between 8.1%-10.4% BF which is a far cry from 16.7% as reported by the scale.
Now, here's where the fun began. I remembered that there are two settings on my scale: normal and athlete. The instructions said that when people with resting HR's of at least 60 that exercise >= 10 hours a week use the "normal" setting, the scale can read BF incorrectly. Aha!
So I set the scale to "athlete" mode without changing anything else, measured myself as I always do first thing this morning and PReSTO! 8.8% which is right in the range reported by the mechanical caliper set.
Besides making me feel better (and less mentally chubby even though I don't have much fat left anywhere) it's good to see that the investment in my scale was not for naught.
If you have one of these scales and have given up on the BF measurements, see if it has an "athlete" setting and compare it to the caliper readings.*
/Hoff
* Yes, neither the scale or the caliper are as accurate as the water displacement tests, but they are important in adjusting diet and exercise routines -- as well as bringing a smile to your face ;)
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