I have been using my Aria for a couple of years now. It is consistently 2% to 4% higher than the InBody at my gym. All settings are identical. Currently, Aria reads 24.0%, Inbody reads 20.7% (or a 3.3% difference) at my current body weight (205) that is roughly 6lbs of added body fat error.
I am posting this now because I had the opportunity to do a water test, I came in at 19.8%. Feeling perplexed, I paid up for a DEXA scan ($175) and came in at 20.2% I am told the DEXA is the most accurate and from the technology, I would have to agree. (the water test is good, but the exhale, hold still approach seems less than scientific).
I will continue to use the Aria as it does seem to provide a good 'trend' for how I am doing and it is easy to use. If you have access to an InBody, it appears to be the most accurate of the resistance scales. They are also really expensive, so adding one to your home is probably overkill. However, if you are truly concerned about the accuracy, I would highly recommend finding a DEXA facility - they can also measure bone density and other health items.
Good luck all.
Moderator edit: updated subject for clarity
