Monday, January 24, 2011

Do I need to make a correction?

After my last blog, a friend of mine chastised me for my measurement techniques and the way I was reporting my weight and body fat percentage values. Of course, if you read my early notes on my measurement techniques, you'll remember that my goal is a relative change and I'm not terribly concerned if my absolute reported value is a few percentage points off. However, she really got me thinking, and I decided to try to learn a little more about a few things.

First thing I needed to do was to understand the different techniques for measuring body fat percentage. Of course, you know I simply went and asked my good buddy Google. He returned all kinds of interesting and informative articles on the different measurement techniques and their relative accuracy. Here's one I particularly liked. That site also has a number of other interesting articles on body composition as well.

Of the different measurement techniques available, there are a few that are more accessible to you and me. I hear that there is a hydrodensitometry weighing tank here in the upstate, there probably are a few, but this is not readily accessible to me on a regular basis. This method is all about measuring the body's density. This comes from the volume displaced by the water, and the weights taken while both in and out of the water. This seems to me the most accurate, but read the articles - no single measurement method is the best.

I'm certain that much more accessible is the use of body calipers. I know that Coach Jeni has a set. She and I will be scheduling a measurement in the near future. In this method, a caliper is used to measure the thickness of a pinched skin sample in 3 or more places on the body. A complex set of formulas is then used to calculate the estimated percent body fat.
If you have a buddy and a set of calipers, here's a cool site I found with the calculations already programmed, you just enter your specific information.

Perhaps the easiest and most accessible method for estimating body fat percentage is through the use of Bioelectrical Impedance. This is where a very small electrical signal is passed through the body and the computer calculates the body fat percentage. This is the method I've been using with my Taylor model 5598 digital scale. Turns out, this isn't necessarily the best method. Worse, the reviews I've read recently on my particular scale are not very positive.

One thing I've learned from this research - I should have been measuring myself in the 'athlete' mode. The scale has two settings according to your fitness or activity level. Wow! What a difference when I switched from the 'non-athlete' mode to the 'athlete' mode. I think the difference has to do with fat that could be contained within the muscles - an athlete is going to have less fat within their muscles than a person who does not exercise.

Yesterday is when I made this switch. In the morning, I was not pleased to see that my weight had continued to drop (down to 167 from what had been an average of 173.5), but it was showing my body fat percentage near 27%! I imagine I am losing some muscle mass while I am on this liquid diet, but sheesh! it can't be increasing my body fat percentage by that much!! So, after that research, I went in and changed the setting on my scale. The Body Fat reading? 17ish percent. Wow, now what?

So, what I'm saying is be very careful and do a bunch of research if you decide you are going to invest in a scale that measures body fat percentage.

Here's an
article on body fat measuring scales:
That same site has a great article on using the skin fold calipers:

For my purpose, I'm going to stay with the 'athlete' mode on my scale, continue to gather the data and I'll continue to report. However, as mentioned, I'll be making an appointment with Coach Jeni to get the calipers
out and make some measurements there.

A couple of other points that I found pretty interesting. Among the methods used to estimate body fat percentage there are a couple of simple methods that use only a tape measure and some calculations. Here's one site that requires some very simple measurements and returned for me a body fat percentage of 18.3%. I'm taking it for what it is, but it will be interesting to see how that number compares to the caliper method and the new readings from my scale in the 'athlete' mode.

I also found this other site that takes you through the method used by the US Navy to estimate body composition. I have not completed these steps yet, but will try to do that today as another estimate to add to my dataset.

So, what is my corrected body fat percentage? I have no idea. However, using the most recent data, I'm thinking it must be closer to 20% than to 24%. The most important thing I found in all of these articles is the same as the approach I have been taking all along - use the numbers as a reference and look for the change in value, not specifically at the absolute value of the number.

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