Body fat measurement – What, how and who to trust!

There are all sorts of ways that body fat is measured, but most (read all) have quite a large room for error. Beyond potential issues with the accuracy of the tests themselves, operator error can throw results off too. So what method should be used for us to measure body fat, and who should we let do it?

The common methods for testing body fat include bioelectrical impedance, caliper testing and mathematical calculations. There are two other somewhat well known methods for testing body fat (hydrostatic weighing and DEXA scans), but due to the high cost of those tests we will reserve talking about them for another point. The short bit on hydrostatic weighing and DEXA scans is that they are by far the gold standard and accuracy is +or- 1.5%, but cost typically ranges between $150-250 per scan, making them unrealistic for most people to utilize for regular monitoring of body fat. SOOOOOOO, on to the rest!

Bioelectrical Impedance is used by a variety of devices such as scales and handheld testers. It operates by sending a small amount of electricity through your body. Muscle and fat have different levels of resistance to electricity, and these machines use the speed of the transfer of the electric jolt, along with the numbers you input into the device in order to calculate your body fat. Hydration levels can affect conductivity creating a large potential for inaccuracy. Lower body fat levels increase the inaccuracy. This method is typically used to create a baseline for measurement changes, but not considered a good way to get a real measurement.

Mathematical Calculations are a simple way to formulate body fat, but don’t actually do it. There are multiple methods used and all take a variety of measurements from the body (such as wrist, forearm, neck etc.) and use that to make an approximation. These methods are commonly used to make body fat assumptions, but are not an accurate measuring method.

Caliper testing is generally considered the best method for accurate reliable inexpensive body fat testing. The test is performed by pinching a fold of skin at 1-12 different points on the body. The number of pinching sites depends on the testing method used. When performed by a skilled practitioner with quality measurement tools, the test is considered extremely accurate. A practitioner should have undergone proper education and spent significant clinical hours practicing. Errors occur when someone measures at inconsistent positions on the body and or pinches inaccurately (pinching muscle or pinching too lightly are the two most common errors). The quality of the calipers is important as well. Calipers are available made of high quality materials and sometimes they are made of cheap plastic that can warp very easily. Because of this, tests should be performed only with sturdy medical grade calipers that won’t warp with use so that you can ensure consistently accurate results. If plastic calipers are being utilized, make sure they have been measured for accuracy, are zeroed correctly and you remember to check these points regularly. The greatest cause of error with calipers is user error, so remember that if the test operator is inexperienced (small amount or no clinical hours) there is a high likelihood of inaccuracy. If you have any reason to suspect a misread, ask the test operator to repeat the test. If they are experienced and performing the test accurately the test numbers should be consistent with a very small margin of error. If you have reason to suspect the honesty of the operator, having them perform the second test without the first test numbers right in front of them should ensure they don’t manipulate their pinch in order to match the first test.

Now for some ugly…

Many years ago I worked at a large national gym which offered regular body fat testing utilizing an electronic plastic caliper system that inputted the pinches into the computer and generated a body fat measurement from the readings. In one particular instance, I along with three other experienced trainers measured a woman at ~23%. I do not remember the exact margin of error between the measurements but I know that every one of the four of us were very close to each other. We all performed the test separately because she didn’t believe the tests were consistent and didn’t trust her trainer at the time. Her trainer had measured her body fat initially at something like 46% (69lbs of fat), and then one month later at something near 30% (42lbs of fat), and she had lost about 10lbs. So if her trainer’s measurements were correct, she would have had to have lost 27lbs of fat, and put on 17lbs of muscle, all in one month. The truth is that her trainer was either inaccurate in his measurements or flat out manipulative and willing to lie to look better. The worst part of the whole thing was that her trainer was somebody of influence at the gym and nobody would have suspected the level of failure this was. I tell you this story just to highlight how important it is to have body fat and fitness assessments done by high quality experienced individuals!


So that’s the who what and how of body fat testing. So to sum up…

  1. Use calipers if possible, and have someone of high quality do it
  2. Use scales and electronic devices as baselines, not accurate methods


Here at TrainBetter, we perform body fat testing at multiple sites, lead by Senior Trainer and Co-Founder Nate Furlong. Nate is highly qualified to perform these tests, ensuring that all of our technicians are accurate, consistent, and trustworthy. If you are interested in having your body fat tested, contact us toll free at 844-Fit-Today (844-348-8632)! Throughout the month of March, at our Wixom location we are offering first time customers their first body fat assessment at no charge ($45 value). Testing spots are limited though, so call now!


Also, be sure to check out this blog post for some great info on fat loss!


Fat Loss and Metabolism: What’s in the Numbers?