Number Crunching

The numbers are getting more interesting

How dissimilar are body fat measurements between caliper skin flold measurements and a Tanita impedence measurement? Not much.

I have data for my tanita scale going back months on end. But I only have five days worth of data for my new skinfold calipers.

date / Tanita* / Skin Fold

04-27 / 22.8% / 23.17%
04-28 / 21.6% / 24.47%
04-29 / 21.6% / 24.81%
04-30 / 20.8% / 24.90%
xx-xx / 21.7 % / 25.15%

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* I use a moving 5 day average for virtually all numbers in my weight loss spreadsheet -- so that the noise gets spread out. Of course, my tanita scale only measures body fat to the nearest 0.5; nonetheless, when using a 5 day moving average, it tends to make the numbers more gradual/sensible.

So it appears either my Tanita scale is understating my body fat by ~3%; or, conversely, my skinfold measurement technique is overstating my body fat by about 3%.

What's interesting is this: I compared measurements taken on the 3rd of the month taken jan-05 through 04-30 (cheated on the last measurement). During this time frame I've dropped from 270 to 230 pounds.

01-03: 36.5%
02-03: 28.7%
03-03: 24.9%
04-03: 23.0%
05-03: 21.7%

So, it would appear I've lost about 15% of body fat. On 01-03 I weighed approximately 270 pounds; therefore, 15% of 270 pounds is approximately 40 pounds. And, magically, I am now 40 pounds lighter.

The numbers work. They always have and they always will.

k

ps - If someone wanted a copy of my spreadsheet -- simply leave your email address on the tag in a comment and I'll send it to you. . . k