This is probably due to the fact that caffeine is a diuretic, and flushes water out of your system. A darker coloured stix is not a good thing. It just means you have more ketones in your urine; and not enough water in your body. Water not only helps flush the ketones out, but it helps you burn fat. If there are too many ketones in your blood, your body wont produce more, i.e. it wont burn fat at its optimal rate. If you are drinking caffinated coffee you need to up your water intake.

Nat