Can I just add that urine ketostix can stop registering ketones for some people after a while, even whilst deeply in ketosis. Once you are not only in ketosis but also efficiently fat burning and using ketones (a few weeks or more) then it might be you are using all the ketones and no longer peeing out excess as you are initially. Blood testing methods, which are more expensiv, overcome this issue if you still feel the need to check. Possibly breath ones too but I’ve never read much into these so can’t be sure. Blood, urine and breath tests measure different types of ketones too.