How accurate is the body fat percentage

[Laurataylor573]

I had my body fat % taken last week and was really shocked (in a good way) to discover I had lost 2.4% since I last had it taken in January. I was 20% and now I'm 17.6%. I think the method used was the Bioelectrical impedance analysis but I'm not too sure. My trainer attaches 2 wires to my right hand and 2 to my right foot. He input my height weight and activity level into the computer and it tells him my lean mass, body fat and water%. What I want to know is how accurate is this method, I had expected to maybe loose 1% but not 2.4%. He did it twice and it came back with the same result.

My weight has stayed the same and I am definatly leaner than I was in January but I just can't help but wonder the machine might be faulty or the result just isn't accurate. Does anyone know of any better methods to take BF%.

[freebirdmac]

Plus or minus 7% and heavily influenced by hydration. In other words useless.

[MrB1g]

Anything where you need to physically enter variables is always going to be inaccurate.

BIA is designed to measure body water, bodyfat % is extrapolated from that. It's complete crap.


If you're that interested, get a DEXA scan (not perfect, but you're looking at a MUCH smaller margin of error) or a water displacement test.

[hamletcat1]

The best judge for determine if you have lost fat is just by looking in the mirror, and if that is the reason you are concerned about fat loss then I would rely on what your eyes see. DEXA scans are very accurate to give you an exact amount of fat mass in relation to your lean body mass (but it includes bone and organs), so it doesn't tell you how much muscle you have. DEXAs are used more for medical reasons or for professional athletes that need to know specific details about their fat/lean body mass.

DEXAs are also really expensive, so not a good way to really track changes. The other methods are ok for tracking changes, but like others have said, can't tell you an exact figure, because most of the other methods extrapolate BF from stats. My understanding is that they are only accurate for people whose body fat is distributed evenly (so for some people they have proven to be fairly accurate).