So I've read on r/keto that you can use a cheap breathalyzer to test for acetone on the breath which indicates your level of ketosis. The trick is to use a cheap, crappy alcohol breathalyzer to test and not an expensive fancy one.
The cheap ones can't tell the difference between alcohol and acetone, the good ones (like the police carry) only measure alcohol and ignore acetone (ketones).
So I bought this breathalyzer http://www.ebay.com/itm/231045711618
And folks in r/keto say that blowing 0.01—0.05 is good and shows youre in ketosis. I just blew 0.14 which I can believe because I've been doing less than 15g net carbs/day this week and I lost three pounds. I put a photo of the readout in my profile pics.
Has anybody else tried this? What reading levels should I be watching for? This seems a lot better than peeing on a stick.