Ways to measure your bodyfat

Electronic scales suck as measuring bodyfat percentage, do not use them

This statement sums that whole article up, yet we are going to explain why and what could be used as a reliable method to track your body fat and progress.

As a personal trainer in Tokyo I face almost every day people being so sure of their body composition because that super expensive scale told it.

Here is a list of methods to check your body composition.

Bioelectrical impedance:

Also known as BIA devices for Bioelectrical Impedance Analysis devices are based on a pretty simplistic idea: muscles are retaining a high amount of water, which is conductive due to the electrolytes it contains, while fat contains almost none. Knowing your weight, your impedance should be reflecting your amount of body fat. Right? Wrong!

This is a very naive way of considering the complexity of the human body. The amount of water in the human body may vary dramatically even in a single day, inducing a delta of up to 9% on an impedance test. This is absolutely unacceptable as a tracking method since 10% and 19% body fat are two different worlds. One would be very lean and the other would be rather fat.

Those machines are even wronger in Japan for expats. They are calibrated upon Japanese individuals which average skin thickness is different than say the western population. Nobody is average! They try to adjust also considering your age to “estimate” your skin thickness, but once again that’s approximation on the top of approximation.

Here is a short list of what could interfere with the result: skin moisture, degree of hydration, time of workout, meal timings, temperature.

So those machines are total  garbage for not only objective value but even for relative value, you can’t even use them as an index of your progression, external factors are way too impactful and numerous. BIA are expensive gimmicky toys, yet they can at least tell your weight correctly, quite expensive for that only function though.

Dual energy X-Ray absorptiometry:

This technique boils down to a radiography to determine your body composition. A single X-Ray source is used to estimate your bone to lean mass to fat mass ratio. This involves more than a simple observation, analysis is done by a software yet to be refined. There are some leading technologies on the market but it is obviously not there for a home use.

Underwater weighting:

Fairly simple, totally based on pure logic, this technique is for sure accurate. The body of the subject is weighted inside and outside of a water pool. Fat being less dense than water, a simple calculation can determine your lean mass. Really accurate but not that portable.

Potassium ion:

Potassium ion isotope can be found withing the cells of active tissues. Determining the total amount of potassium ion is an indirect yet accurate way of determining the amount of lean tissues in a body. That’s obviously only possible in laboratories at the time this article is written. Also quite expensive, compared to methods like underwater weighting, this is much more of a proof of concept.

Nuclear magnetic resonance (NMR):

Does not sound like something you can do in your favorite gym’s locker room, right? Certainly not, that’s hospital level technique taking advantage of the fact that tissues and more exactly nuclei are resonating at a particular frequency depending on their nature. To back the data collection, serious computing power should be used. A perfectly accurate method but not yet to be installed between the lockers and the vending machine.

Ultrasound:

More portable, this technique could be used by some physicians. Working the exact same way than the echography, the machine is used this time to measure the thickness of the fat layer.

Near infrared interactance (NIR):

This technique is fairly new and studies suggest that this technology should be improved to really be considered as accurate. A probe is placed over the bicep. This probe emits an infrared beam passing through subcutaneous tissues before getting reflected by the bone. Some gym maybe have this pretty inexpensive device but its lacks of refinement pushes us to not advise it as a measurement tool yet.

Skinfold thickness:

This is one cheap and reliable method. An estimate of the body fat is made by measuring the thickness of the skinfold at strategic places. Approximately 50% of the body fat is subcutaneous. Therefore, there is a direct relationship between the average skinfold thickness and the actual body composition. A specially designed skinfold caliper has to be used throughout the body at representative sites. The measurements are then converted into a body fat percentage. This technique is inexpensive, portable and appropriate for both laboratory and field settings providing it is operated by experienced and skilled individuals.