Why Body Scanners and Body Fat Scales are Poor Ways to Track Body Composition
We’ve had salesman try to flog us body fat scales, InBody scanners and other equivalents over the years. Their sales pitches and marketing all sound great and they try to convince you that these are must have tools.
Don’t fall for this, it’s just marketing to get you to part with money for their product.
They’ll reel off the long list of “pros” that their machine will provide.
However, they fail to mention the huge flaws these gimmicks have, which when you understand how they work, you’ll realise how pointless they are.
The major floor is they rely on bioimpedance. Bioimpedance sends an electrical current through the body to measure resistance. Fat free mass contains a high percentage of water so will provide less resistance, fat (or the lack of water it contains) will provide more resistance. The claim is that this resistance measurement will tell you how much fat you have.
There are a number of problems with this. Firstly, you can actively distort the result. If you take the test more hydrated it’ll tell you you’ve lost fat. If you’re dehydrated it’ll produce a higher fat result. Both of these outcomes have nothing to do with how much fat you actually have!! So if you want a lower body fat percentage on a body scanner, just take the test really well hydrated. Also, unless you’re taking the test in a consistently temperature controlled room, the weather will distort the result. You’ll get lower readings in the summer when its hot and sunny as you’ll be warmer. This is also true of taking readings after training. All bad news for the validity of the result.
Secondly, they are just not that accurate. Regardless of manufacturer claims, there is an accepted inaccuracy of about 5% either way! (I’ve tried an InBody scanner for 2 consecutive readings and got a 7% difference in outcome!!) This means if you’ve actually got 15% body fat, you’ll probably get a result anywhere between about 10% and 20%. That’s way too big a swing for the result to hold any value. At the very best your “result” is a rough estimate.
Thirdly, maybe not for all, I haven’t tried every brands machine, another interesting way these machines are flawed is that they often require you to input your age (which has no bearing on your actual body fat). While this may seem incidental, I’ve personally tried a few different ones and if I take the test entering my actual age, then immediately take it again entering a lower age, my result shows a lower body fat percentage the second time. I didn’t lose fat in that 2 minutes so the machine is is using the prediction that we lose muscle as we age, not measuring my actual body fat.
Lastly, electrical current will take the shortest route through the body to link the sensors. On body fat scales the current will travel up one leg, across the pelvis and down the other leg, not recording anything above the pelvis. Handheld versions miss everything below the chest as the current goes across the arms and chest. Even cross body versions don’t measure the entire body, despite claiming to give you an accurate segmented break down.
On all bioimpedance based machines, the “result” you actually get, is at best, a pretty inaccurate estimate for a section of your body. Not much use right?
Instead, why not use ways of tracking that will give you an accurate measure of your progress. These ways of tracking have been successfully used by all body composition competitors for years. They don’t come with some jazzed up marketing or sales pitch (because they don’t need it, they’re not trying to hide any flaws) and they’re always reliable. AND, as an extra bonus, you probably already own them!!
So what are these “special” tools? A mirror and/or a camera. They’re fast, simple and always accurate, unlike all that gimmicky body scan guff.