Vastly different body fat % results from digital vs. calipers. What to believe?

kampshoff

I had a free session with my wife's trainer at our gym, and after the session, we measured my body fat percentage with one of those handheld devices. I've lost around 20 pounds since the beginning of the year, so I expected to see a marked improvement; unfortunately, I don't remember what my body fat percentage was the last time I had this done. I think it was in the low 20s.

The readout came up at 9%, which we both agreed was probably impossible, so she suggested calipers. She did two measurements, and came up with 15%, which is much more reasonable.

My questions are: What causes this huge disparity? Is the calipers method generally reliable? What could have caused the digital device to malfunction? Am I actually super lean and fit and this whole pot belly thing I have going on an illusion?

juggernaut1974

Neither is particularly accurate. Calipers can be slightly more so, assuming the person using them is trained how to use them correctly.

The digital scales work via electric signals that measure conductivity. Since water is conductive, being more or less hydrated can create wildly inaccurate results.

Zedeff

Do you have visible abs at rest? If so, then 9% might be accurate. Do you not? Go by 15% (or higher).

The absolute body fat percent doesn't matter. Pick a method and be consistent with its application and sets goals by changes in the metric. You want a method to be precise even if it's not accurate.

keithcw_the_first

I think hydration can have a big effect on the body impedance devices. The calipers have a margin of error too but I want to say it's smaller, although it can be more pronounced if the measurements are not made consistently and correctly. Being an inch off could really impact the reading.

If you're really curious, I'd pick up a $5 set of calipers from Amazon and check it every few weeks. Even if you're a little wrong, as long as you're consistently wrong you can spot trends.

And there are a lot of places online with pictures of people at various BF% for reference so you can kind of do a sanity check that way as well.

9% probably would have you with visible abs, or at least the top part and higher visible vascularity all around. 15% would not, so there's that too.

kampshoff

Haha, definitely no visible abs, though I can see my ribcage for the first time in a long time. I never had any illusions that the 9% was anywhere near accurate. The potbelly is the last fatty "trouble spot" I've got left, and it's stubborn...

Are the impedance devices (scales, etc.) precise enough to be useful, given a large enough sample size? I weigh myself in the morning, and I don't see myself having the patience for doing a caliper reading consistently. I've been thinking of investing in one of the fitbit scales that do this, since we've already bought into the fitbit ecosystem.