THE LACK OF ACCURACY IN BIA BODY FAT TESTS
Bioelectrical Impedance Analysis, otherwise known as BIA tests, is the body fat analysis that you either “Stand On” or “Hold with Both Hands.” For simplicity, I will just call them both BIA tests.
Here is a little blurb about me and my background so you determine if my opinion on this topic is credible, or not. I spent over $300,000 and several years of my life making a living giving people, (including professional athletes and competitive bodybuilders), the truth and PROVING that BIA tests are a waste of your money and your faith. I owned and operated a Fitness Testing Lab, providing Hydrostatic Body Fat, Basal Metabolism, VO2 Max and Antioxidant testing to teach people that "general math equations" don't know their specific body and it's needs, (just easy for generalizations)... and to prove that BIA tests are a waste of time and money. I personally own the top-of-the-line Tanita BIA scale, that I bought just to prove their inaccuracy… NOT to test anyone’s bodyfat.
The test known as the “Golden Standard” (most-trusted), in the history of Body Fat tests is Hydrostatic Body Fat Testing, which is the equipment that I had in my Fitness Testing Lab. In recent years, the DXEA test has also proven itself extremely accurate, as well as Bod Pod tests on the average person, (female athletes often get faulty readings with a higher than acceptable error margin). The error margin for HBFT is 3%. That means body fat tests a 200 lbs woman at 30%, her true body fat is 27-33%. Most errors of HBFT are caused by people not getting all the air out of their lungs for the test. This method tests ALL their body fat, not just the external body fat that you can visually see or pinch above the muscle, but also calculates the fat that you carry between your organs too.
Here are a few reasons why BIA’s are FAR from accurate.
1) Hydration Levels SEVERLY skew the test results. If I get on the Tanita today, and my hydration level reads 46%, my body fat might show as high as 38%. If I get on the scale tomorrow at the same time and same weight, and my hydration level is 50%, my body fat will show as low as 23%. The dramatic difference of 23-38% is HUGE. That is MORE than 3 times the error margin for only a 4% change in my hydration level. (Keep in mind that the Error Margin alone is LARGER than most people will lose from dropping 34 lbs on a round of HCG… so it would be impossible to use this type of device to determine if you lost muscle)
2) The “Stand-On” types also give false readings if your thighs touch when you are standing on the scale. They operate by shooting a tiny electrical impulse up one leg and out the other. If their legs touch, the impulse is redirected through a much shorter route in the body and does not “read” the body fat levels correctly. Even somebody that is only 30 lbs above their ideal weight will often have their thighs touch, so this is hard to do on any normal-sized scale.
3) If you are still not convinced, then ponder this… All the NEW and IMPROVED BIA analyzers have a feature called “Athletic Mode,” (or something similar). When you switch to this mode, none of the other data you entered changes, but magically, your body fat decreases. ????Oh Luuu-cy, can you explain this???? (my dumb attempt at adding some humor… “I Love Lucy” style). If these BIA scales could ACCURATELY measure your true body fat levels, why does it have to ASK you how often you work out?? It should be able to determine that you have more muscle on your body than the average person who doesn’t exercise.
In conclusion, I consider BIA tests the “cheapest and fastest” way to get a body fat reading… and the worst least accurate reading you can get. It is perfect for the microwave world that we live in because people want things fast and cheap… and although that makes things more popular to the masses, you lose quality and reliability…and somebody makes a profit on you wanting the information, regardless of how inaccurate it is. (It’s just like cheap cell phone providers that drop calls frequently…. I’d rather pay more and get quality service, so I stick with Verizon)
ADDED INFO FOR REFERENCE
Here is a copy and paste from Tanita’s website… the industry EXPERT in BIA devices:
The Athlete mode was developed to provide a more accurate reading for athletic body types. Athletic body types are physiologically different than standard adult body types, due to muscle mass and hydration level differences. Athletes tend to have greater muscle mass and tend to be more dehydrated. These differences would skew the body fat reading high, when taken with the standard Adult mode.
MY COMMENT: Aren’t athletes HUMAN. Don’t they have muscle, water, bone & organs, just like everyone else???
Here is a copy and paste from Wikipedia….
The Bioelectrical impedance analysis (BIA) method is a more affordable but less accurate way to estimate body fat percentage. …. As technician error is minor, factors such as eating, drinking and exercising must be controlled since hydration level is an important source of error in determining the flow of the electrical current to estimate body fat. As men and women store fat differently around the abdomen and thigh region, the results can be less accurate as a measure of total body fat percentage. Another variable that can affect the amount of body fat this test measures is the amount of liquid an individual has consumed before the test. As electricity travels more easily through water, a person who has consumed a large amount of water before the test will measure as a lower body fat percentage. Less water will increase the percentage of body fat. Also reducing the reliability of this method is the variation between models of the BIA devices: for instance when comparing outputs from a Tanita scale to an Omron Body Logic handheld device the Tanita scale overestimated the percentage body fat in college-aged men by 40% and in college aged women by 55%.
MY COMMENT: Did you catch the LAST sentence??? They can give you readings with as much as 40-55% ERROR!! That is HUGE! (and more trustable since it is NOT from a salesperson’s website)