How accurate are the fat% scales?

Pugwash4x4

Anyone have any experience of the accuracy of the impedence measuring weight loss scales?

would be happy with +/- 2%, but I have no idea if that's reasonable.

Jimzilla0

Not quite what you are asking, but I have some Salter scales that do bioelectric impedance analysis, and readings on successive days jump up and down by up to about 2% each day, even when my weight has remained totally static, which means that it's quite tricky to use the number as a metric to game without taking an average over quite a number of days, in which case it does give quite a useful signal. During the first almost-a-week of my regime the average stayed pretty static while I was losing weight really quickly. After that, the average of the % fat readings started to drop, and my weight loss slowed down. I'm interpretting this as the first week of weight loss being mostly "water weight" (glycogen stores) which didn't affect my % body fat, and then after the first week that was gone so I started burning actual fat.

I think maybe what you are actually asking is how accurate the measurement is compared to true body fat, which is a much harder question. I think that even standard measurements of body fat (pincers etc) are less than 2% accurate, and from my research I gather than BIA is definitely less accurate than than those, because they are based on a statistical model of a standard person of particular height/weight. I think to get better than 2% accuracy you would have to do some quite difficult measurements - water displacement etc which probably aren't going to be practical for daily monitoring of your diet.

Regards,
Jim

kirkor

The accuracy varies widely based on how hydrated your body is.
Better to use just the weight function, and take tape measurements & photos to gauge progress.

Phrick

They're not accurate, really. Too many variables.

AdrianBry

least accurate. if used has to be done first thing in morning, can't drink anything, etc. and even still it's not dead on or even close.

a multiple site caliper test is probably the most accurate you'll get unless you do underwater weighing or a bodpod

294Rich

I've read the small print on one of these.

They are very inaccurate.

Apparently, if you don't have enough water in you, they say your fat % is too high. If you have "too much" water in you, they say your fat % is too low. Seems the only thing that they can actually monitor is you hydration level, which is useless.

gracielynn1011

I'm pretty sure the only time mine is accurate is when you are standing on your hands under the light of a full moon while chanting a weight loss mantra.

Any other time, it shows my reading at approximately double what it really is. That purchase was the biggest waste of money I ever made.

AdrianBry

I've read the small print on one of these.

They are very inaccurate.

Apparently, if you don't have enough water in you, they say your fat % is too high. If you have "too much" water in you, they say your fat % is too low. Seems the only thing that they can actually monitor is you hydration level, which is useless.

never knew about the small print. A lot of people at the YMCA I work at ask me all the time about whether they should get one or not. now I can tell them even the people who make them say it's not accuarate

294Rich

Don't get me wrong, i don't make them. But I have read the small print on the instructions that come with these machines/scales. You can see them is you google for them, and download a pdf of the instructions. The information about their accuracy is quite damning!