Friday, February 29, 2008

How to Guide: Measuring Body Fat

"The devil has put a penalty on all things we enjoy in life. Either we suffer in health or we suffer in soul or we get fat." ~ Albert Einstein

Lately I've been reading a lot of other bloggers weight loss blogs & I've noticed that many of those who list there body fat % on their site have much lower percentages than I do. I started to wonder just how accurate my body fat % actually was.

For those of you that don't know my body fat % listed on this blog is based entirely on the results given by my Tanita scale. For additional information on how often I weight myself & how I tabulate my numbers click here.

After asking around a bit and finding out others peoples methods I figured a little research was necessary on my part to figure out the following:
  • How many different methods are there?
  • How accurate is each method?
  • What method will I use for my blog? (if I decided to change methods).
After a few hours of probing the internet, some in-depth reading, and some number crunching this is what I came up with:

~ How many different methods are there?

In short a lot.... however there are 10 methods that are more commonly used by gyms, at home, and by the scientific community. Out of the 10 methods only 3 are easily accessible by the typical weight loss blogger (bolded). Here are all 10 methods listed in alphabetical order:
  1. BIA Bioelectrical Impedance Analysis
  2. BOD POD (Air Displacement)
  3. Calipers (Anthropometry - Skinfold Measurements)
  4. Computed Tomography (CT....know as CT Scans)
  5. DEXA (Dual Energy X-ray Absorptiometry)
  6. Hydrodensitometry Weighing (Underwater Weighing)
  7. Magnetic Resonance Imaging (MRI)
  8. NIR (Near Infrared Interactance)
  9. Online Body Fat Calculators
  10. Total Body Electrical Conductivity (TOBEC)

1. BIA: sends a weak electrical current through the body, via bodily fluids/water. The current travels faster through areas with a high water content such as lean muscle mass, while it slows down through fat. The current returns to the originating source and the impedance (total electrical resistance) is measured using a scientific formula (Z = R + iX). The impedance measurement combined with the individuals, height, weight, and body type (age, gender, fitness level) allows for the estimation of their body fat percentage. BIA is the method my scale uses.

Pro's: Quick and easy to use. Relatively inexpensive. Widely available.
Con's: Test is affected by food/water intake, so it's necessary to use this method under consistent first thing in the morning, after visiting the bathroom and before eating/drinking.

3. Calipers (Anthropometry - Skinfold Measurements):
"Using hand-held calipers that exert a standard pressure, the skinfold thickness is measured at various body locations (3-7 test sites are common). Then a calculation is used to derive a body fat percentage based on the sum of the measurements."
~ New Fitness
Pro's: Easy to do. Inexpensive. Widely available (personal use or by a trained professional)
Con's: Test results are subjective (depends on: quality of calipers, skill of the person taking the measurements). Also the more obese the subject being tested, the harder it is to get an accurate measurement.

9. Online Body Fat Calculators:

Online body fat calculators can be found all over the internet. They calculate your body composition based on measurements taken at various parts of the body. The calculators take this information, feed it through some type of a formula, which gives you your body fat %. The area's measured, and the formula used varies depending on the site visited and the criteria of the the calculator being used by that site.

Pro's: Free & easy to do. Available all over the internet.
Con's: Test results vary significantly depending on the testing criteria & source. Very generalized. Can be inaccurate.

If you are interested in learning more about the other testing methods not discussed read the following article by

~ How accurate is each method?

Of the 3 methods accessible by the typical weight loss blogger, body calipers are considered to be the most accurate, but only if the test is done by a trained individual, using quality equipment.

BIA testing used by scales comes in second, but it's important to keep a steady hydration level and test under consistent conditions for accurate results.

Online body fat calculators finish last. Results can be all over the board, but if you don't have access to the above 2 methods it can at least give you something to gauge your progress by.

~ What method will I use for my blog? (if I decided to change methods).

I've never had the opportunity to try the caliper method, however I would be willing to give it a shot in the future.

Using my scale my current body fat % as of this morning is 35.1%

Here's a list of some online body fat calculators that I found on the internet, and my body fat % calculated by them using today's measurements: = 26.1% body fat. = 33.0% body fat. = 34% body fat. = 34.1% (US Navy Formula) & 31.3% (YMCA Formula) = 36.3% body fat. = 33.9% body fat. = 34.1% body fat.

If you use an online body fat calculator that you believe is more accurate and isn't listed above, let me know and I'll add it to the list. Based on the 3 methods accessible by the typical weight loss blogger, I think I will stick to my scale. After all it's already paid for.

I hope this post has been useful. Let me know if I missed anything, made any errors, etc.

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Blogger Fat Lazy Guy said...

Nice and informative post. I think it'd be really awesome if you could follow up with the other 7 methods you mentioned in future posts. I don't know how feasible that'd be :D But I think it'd be cool to follow up on.

9:27 a.m.  
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Blogger Alexa Anderson said...

I didn't know that body fat can be measured with FT NIR. How do they do it? Do they use NIR analyzer or NIR spectroscopy for it?

10:10 a.m.  

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