T Nation

BF% Scales..

I remember a couple of years ago in high school they checked our bf% with a little scale that read the bottom of your foot. Are these things accurate or no? -jimbo

No. Not accurate. I am currently at 10% and have used calipers and an omron and recieved 8-12% with the type of scale you decribed, I know tanita makes some, I have had readings of 24%+.
Greg Gonzales

Not according to almost everything I’ve read, and from my personal experience…my Tatana gave me a reading of 30% this morning, while the calipers gave me 16%. I know what 30% looks like (having been there at one time), and I know I’m not 30%. Just about everything I’ve read says the electric-impedance(sp?) scales for home use are notoriously wrong - your hydration level alone can make a difference of several percentage points.

I have a tanita scale and I get readings anywhere from 8-17% throughout the day.I am about 10-12% with calipers. I don’t think they are too accurate because you have to enter height and a difference of a half of inch can mean a whole percent of body fat.

They are the least accurate means of measuring bodyfat. They don’t read the bottom of your foot, they send an electrical pulse through your body. The worst thing about them is that I have never seen one with a percent error.

Not accurate.

There are way too many variables to take into account when you use bioelectrical impedence. The biggest one is hydration status. The whole idea is that since water is a good conductor of electricity, someone with more muscle (which equals more water, primarily from stored glycogen) would be able to conduct the charge quicker than someone with more fat (a poor conductor, because it contains very little water). So, if someone who is ripped but dehydrated steps on the scale, he would receive a reading that was much too high. Some of the most expensive models have a built-in function that measures hydration, but if you’re going to spend that much money, why not just pay for a hydrostatic weighing test? Your best bet is a happy medium between the two, so stick with the calipers.

I’ve got the Tanita 612 which has the athletic mode. By calipers I’m 10-12%. By the scale I’m 17% in the morning and about 12% at night. My gf hates the scale…calls it “The Fortune Teller”.

If you have a point in your day that you usually have about the same hydration and activity level, it can be a good way to track your % body fat. Problems arise when you do it at different times in the day. I use mine right after I’ve gone to the bathroom and before I’m about to start my workout. Usually 4-6pm and I usually see a 2% variance that I can predict because I know my hydration level varies a little. By the way, no method for body composition is going to be pin point accurate. They all have significant problems. What you need is to find a measure that is precise and reliable. Precise and reliable means that it will give you the same measure of % body fat each time (as long as it has not changed). Most techniques, even skinfolds and bioelectrical impedance, are going to give you accuracy that is fairly close. You just have to make sure that you are consistent every single time you measure.

I have a Tanita. It’s pretty inaccurate, even from day to day at the same time of day. I gave up and started measuring my waistline with a tape measure.

I got measured twice out my doctors office on the tanita and i had readings of 18 & 19%. I was devasted at first but then I rwealized that can’t be accurate especially since I can see two of my abs and 4 sometimes.