How to measure body fat accurately
We’ve learned plenty about how to measure body fat since we opened our own body scanning service. There’s a few ways to do it, but not many ways to do it well.
We’ll put our biases up front; we are a 3D body composition scanning business. We chose our Styku scanners because we think they give the best results relative to the scan cost for customers, and the hardware cost for us. We like to be open and honest about our service and competing services so we put this guide together for people as a starting point for researching how to measure body fat.
HOW TO MEASURE BODY FAT
We’ll give some clarity on what we mean by “how to measure body fat” before we jump into the discussion. There’s only one literal way to measure body fat; remove it from your body and weight it. That’s not pleasant or feasible for obvious reasons, so what we’re talking about here are ways to accurately predict body fat. All of the methods below are predictors rather than true fat measurement devices or systems. It’s a small but important semantic difference.
ONLINE FAT CALCULATORS
We’ll start with the easiest and most entertaining way; online tests.
We’ve done a whip around the internet and tested several data input calculators that use easily available body data to make a prediction of your composition because. Height, weight, and a couple of circumference measurements is all they need to estimate your body fat. Generously put, they’re rudimentary and tend to be based on very broad and generic data.
They might put you close to your actual percentage but there’s a wide margin of error. I have all of the accurate height, weight, and circumference data needed and still I’ve been quoted: 2.8%, 4%, 0.92%, 9%, 28%, and multiple 0% because it can’t understand my skinny waist. For reference I’m 13.8%.
In short: Funny, might get within a few percent if you’re inside the calculation range, but not very useful.
BODY SURFACE SCANNER
We use Styku body surface scanners to measure body fat in a way that emulates a DEXA scanner.
The 3D body scanner takes over 600 infrared images of your body as a platform rotates for 35 seconds, then compiles a 3D model of your body. An algorithm uses the circumference measurements at specific body landmarks to then calculate your body composition with fat mass, lean mass, and bone mass included.
The algorithm was developed to emulate DEXA scan results. We wrote a comparison article about getting a DEXA scan and body surface scan in the same day to directly compare them if you’d like to see how similar the results are. As stated above, we bought them and believe in them. We’ve been impressed with the consistensy and accuracy.
In short: A modestly priced and convenient way to get very close to DEXA scan results.
DEXA (Dual-Energy X-ray Absorptiometry) scanning is widely regarded as the most accurate way to measure body fat, body composition, and bone density. We have no reason to disagree, DEXA machines are good at what they do.
You lie on your back for several minutes while the DEXA machine slowly passes over you. It uses very low amounts of radiation to determine your composition with high accuracy. Reports will have plenty of detail with totals and regional fat and lean mass distribution, explanatory paragraphs on what each metric means, and x-rays of your skeleton and fat distribution.
DEXA machines are large and expensive so they’re not always conveniently located or available to the public for anything other than medical uses. A DEXA scan is expensive too, usually starting at $90 or so.
We got our own DEXA tests and compared them to body surface scanning.
In short: Expensive but accurate. Still the best for medical applications.
Calipers deserve a Lifetime Achievement award for services to measuring body fat, but should probably slip into a dignified retirement as newer and better measurements are available.
Caliper body fat measurement is based on solid scientific research but the rudimentary measurement system, and need for accuracy and consistency means results are highly variable. It’s also unpleasant to be grabbed and pinched.
Caliper/skinfold tests involve pinching between 3 and 7 areas of skin and measuring thickness. A calculation extrapolates those values into a body fat percentage. Our Styku 3D body scanners use the same basic principle; using external body measurements to calculate internal composition. The caliper testing results need to be done skilfully to get reliable results. Small errors in the body landmarks that get pinched can add up to large errors. Differences in technique can also cause errors.
In short: Cheap & backed by solid scientific evidence. It can get you “about right” if done properly. Not very dignified.
BIO-IMPEDENCE ANALYSIS (BIA)
This is a large, and tough market segment to analyse because of how many devices use BIA measurement.
BIA machines measure body fat by sending electrical currents through your body and reading how much resistance they meet. Electricity passes through muscle much easier than fat, so the resistance is extrapolated into body composition values.
Good quality BIA machines can be accurate but factors like hydration, food, physical exercise, and alcohol can have significant effects on results.
The vast range of devices means it’s impossible to sum up the technology or make blanket judgements on their quality and accuracy. Everything from $150 smart scales, $30 handheld devices, through to $30,000 and higher static scanners with 4 contact points fall into BIA machines.
In short: Widely available and long-running tech but not all devices are created equal and can give highly variable results depending on what the person being scanned has done in the hours before.
AIR DISPLACEMENT PLETHYSMOGRAPHY (ADP)
ADP measuring is a strange process that involves people wearing very tight clothes and sitting inside an egg-shaped chamber while the machine alters the air pressure. The machine determines your body density from how the air pressure changes while you’re in the chamber. It’s widely regarded as accurate and takes only several minutes.
It’s expensive, as you’d expect from looking at the hardware, like DEXA scanning. Most ADP hardware is used for research or medical purposes so they can be hard to find. We could only locate one machine in Australia.
In short: Accurate, pricey, and a little bit hilarious. They’ll give good results if you can find one.
As stated above, we feel the Styku 3D body scanners give the best bang-for-buck body fat measurement, and gives a substantial data suite to go along with it. For those who need very high accuracy, or have a specific medical requirement, we’d recommend DEXA scanning. It’s still the absolute best.