There is no BMI measurement that use's electrical current. That's a body fat index which is very different and much more precise. BMI is a very poor and ultimately very hard to justify formula that only takes into account weight/height sorted by gender. Things like muscle index and body frame are completely ignored and often lead to very poor BMI's for people who shouldn't have them.

Maybe bargl means Bioelectric Impedance Analysis? A cursory internet search also indicates BIA is suspect as a one-time measure.

OK so I have this and I thought that the BMI it computed was based on tracking the fat to everything else based on BIA. But I may be way off here.

https://www.fitbit.com/aria

I see that Fitbit tracks this as BodyFat % not BMI. Not sure if that's accurate.

BIA is pretty bad. Here are ~1300 Fitbit Aria measurements matched against 7 DXA scans. The Fitbit bodyfat data (teal) is just random noise and can barely detect considerable changes in body composition.

http://i.imgur.com/J4Ls2bQ.png

I stopped paying attention to be BMI, I'm 6ft, 190lbs and have a 32" waist and it has me right on the edge of been overweight.

I think given that many people don't realise how inaccurate it is I might even class it as harmful.

You are on the edge of overweight, and you don't realize it because of all the fat people around you.