Measuring Body Fat…. Eeeeeeewwwwww!!!!!!
Body fat can be measured in several different ways:
- Biopsy This is a medical procedure which requires sticking a large needle into your body, kinda like a geologist doing a core sample. The sample of muscle and tissue is analyzed and the percentage of body fat to muscle along with a whole host of other tests can be performed to determine whether you are world athlete potential or not.
Since I already know I’ll never be in the next Michael Phelps or win the Tour de France, AND I hate large needles, I decided that I wouldn’t pursue this option. Did I mention that it’s very expensive? It is, however, the most exact method.
- A host of new fangled TECH-KNOWL-E-GEES with jaw breaking names:
• DEXA (Dual Energy X-ray Absorptiometry)
• NIR (Near Infrared Interactance)
• Magnetic Resonance Imaging (MRI)
• Total Body Electrical Conductivity (TOBEC)
• Computed Tomography (CT)
I’ll spare you the gory details about how all these work. If you’re really interested, you can visit this cool page I found at the University of Vermont where they have this interactive tutorial that talks about some of them. Basically when all is said and done, they all have pluses and minuses. And any number you get back is basically an estimate. A very expensive estimate. And since I’m a workin’ man and can’t afford any of these expensive high-tech ways to tell me just how fat I am, we’ll move on to some options that a regular middle class fella can afford.
- Underwater buoyancy test also known by the jaw breaking phrase “Hydrodensitometry Weighing“ or “Hydrostatic weighing.” This is the one of the best non-invasive methods. The equipment can be found on most college campuses, in medical facilities, in the better gyms and health clubs and it is available at a cost that, while not cheap, is manageable.
Basically you weigh on dry land then you sit in this chair that looks like what you’d find on a kids swing set and they lower you into a tank of water. You blow out all the air in your lungs and lower your head under the water. Then you stay in this uncomfortable position while the numbers on the scale stop jumping around and the attendant takes the underwater weight measurement. A formula which factors the difference between your weight underwater and your weight on dry land produces the percentage of body fat. While the number you get back is still an “estimate” it is a highly accurate estimate. Check out the page at the Univ of Vermont for more info.
- Caliper method This is the usual method involving measuring the amount of subcutaneous fat by pinching the skin and fat then measuring the fold of skin and fat with calipers. You can get it done at just about any health club or gym. The test can be done with three measuring points or with five. The five point method is slightly more accurate.
The main advantage is that the tools are cheap, under $5 and it is quick and easy. A good tester can produce a result that is nearly identical to the results from the underwater test. However two different testers can produce widely different results depending on how much they “pinch” so the upshot here is that while a good tester can produce excellent low-cost results, a bad one can really give you an inaccurate assessment.
- Bioelectrical Impedance Analysis Everybody knows that metal transmits electrical current better than cotton. In BIA same principle is applied to body parts: A very low voltage electrical current is passed through the body. Muscle, bone and fat all transmit electrical current at different levels of efficiency.
By measuring the impedance of the current, it is possible to calculate the amount of body fat. The least accurate of the three methods, the test results can fluctuate widely depending how hydrated your body is, what time of day you weigh or the humidity in the air.
Good for home use because of its low cost and convenience. If some basic steps are followed, it can provide a good “relative measurement” to track your progress.
Here is how I do it:
I use the TBF-531 Body Fat Monitor/Scale by Tanita. (Note: This model is no longer manufactured, but they have newer models that do the same thing)
I also use the Omron Fat Loss Monitor HBF-306. Both devices use the electrical impedance method of measurement. I take two measurements, one from each device and then average the two numbers.
The user manual for the Tanita is much larger than the Omron so I’m going to use that manual as a basis of discussion for the rest of this blog post. In comparing the Tanita user manual to other information I’ve read I’ve concluded that the information from the manual is basically accurate. It is, of course, written in such a way as to make their product sound great and awesome and the best scale created since the building of the pyramids, but hey they have to make a living too. 😉
Excerpt from the TBF-531 Owner’s manual
Body fat percentage is the percentage of fat in your body. Until now, your absolute weight has determined whether or not you were considered obese. In recent years, the definition of obesity has been refined to mean the presence of excess body fat. too much body fat has been linked to conditions such as high blood pressure, heart disease, diabetes, cancer, and other disabling conditions.
Comment from little ole me: The figures in this chart while given in a very broad range, are fairly accurate. I’ll do a later post that talks about “What is a healthy body fat percentage?”
Body fat percentage measurement (From the Tanita Manual)
The TBF-531 uses the BIA (Bioelectrical Impedance Analysis) technique. In this method, a low-frequency electrical current is passed through the body. It is difficult for a current to flow through fat in the human body, but easy to flow through moisture in the muscle. The current used for measurement is very low, making it safe and imperceptible.
Comment from little ole me: There are lots of warnings all over the box and in the owner’s manual that folks with pacemakers, children 7 yrs or younger, adults 70 yrs or older, pregnant women, persons undergoing dialysis, persons suffering from edema should not use the device. Their lawyers probably wrote those warnings so they wouldn’t get sued but hey, why take the chance. If you fit one of those categories, you might want to rethink using BIA.
Body fat percentage fluctuations in a day (From the Tanita Manual)
For the most accurate reading, a person should measure body fat percentage in the evening before sleeping because electrical resistance usually increases during sleep and decreases when the body is active. While readings taken at other times of the day may not have the same absolute value, they are accurate for determining the percentage of change as long as the readings are done at a consistent time every day.
Besides this basic cycle of fluctuations in the daily body fat percentage, variations may be caused by changes of moisture content in the body due to eating, drinking, menstruation, urination, illness, exercising, and bathing. Daily body fat percent fluctuation is unique for each person, and depends upon their electrical resistance cycle, life style, job and activities.
Comment from little ole me: Basically what they are saying is: You have to be consistent. The measurement is dependant on a lot of things which affect the electrical flow, specifically the level of moisture in your body. If you are dehydrated, you’ll get a different result. If you just finished exercising. If you are under a lot of stress, then that affects it. If you just stepped out of the shower and are still damp, that will affect it. So… now you see why I’m using the averages of the two daily measurements and a weekly average as well.
Advantages of the Tanita TBF-531
Comment from little ole me: I’ll spare you the advertising blurb about how good their product is. Let me summarize instead. Of all the methods I’ve listed here, BIA will probably work best for most folks because it is easy, inexpensive and if used consistently can provide a good relative measurement.
The BIG (pardon the pun) advantage of a home scale like this one is Uhmm. Duh, It is in your home! Even if the results are subject to a wide range of environmental factors and the testing method is the sometimes inaccurate, the advantage of being able to conduct the test in your home on a daily basis outweighs (again, pardon the pun) these disadvantages.
It also has the advantage of being PRIVATE; no ex-marine sumo-gym-teacher type is going to look upon my vast acres of blubber and make me pay for the privilege of having him pinch me or dunk me then tell me that I’m out of shape and overweight. This I know already. So, I take my own measurements in the privacy of my bathroom where no one can see my naked body and run screaming (or have to schedule a session with their therapist) and use those measurements as a relative measurement not as an absolute one.
See ya on the dance floor!
Related articles and Links
- What is a Healthy Body Fat Percentage? (txcowboydancer.wordpress.com)
- Methods of Body Composition Analysis Tutorials (University of Vermont Dept. of Nutrition and Food Sciences)
- Underwater Weighing (Composition Analysis) (University of Vermont Dept. of Nutrition and Food Sciences)
- DEXA Dual-Energy X-Ray Absorptiometry (University of Vermont Dept. of Nutrition and Food Sciences)
- TOBEC Total Body Electrical Conductivity (University of Vermont Dept. of Nutrition and Food Sciences)
- BIA Bioelectrical Impedance Analysis (University of Vermont Dept. of Nutrition and Food Sciences)
- Body Fat Measurements (eHow.com)
- How Fat Cells Work (HowStuffWorks.com)
- The truth on losing abdominal body fat – forget the diet hype, here’s how it really works (naturalnews.com)
Posted on Fri, Mar 12, 2010, in Misc and tagged Adipose tissue, Bioelectrical impedance, Biopsy, Body fat percentage, CT, DEXA, Dual Energy X-ray Absorptiometry, Hydrodensitometry Weighing, Hydrostatic weighing, Magnetic resonance imaging, Measuring Body Fat, Michael Phelps, MRI, NIR, TOBEC, underwater weighing, University of Vermont. Bookmark the permalink. 1 Comment.