The strips aren't entirely accurate; some people are in ketosis and ketones will never register on the strips. And the darkness makes no difference in the amount of fat that you are burning - they are just evidence that you are burning fat. There isn't a whole lot of info about ketosis on this site or in P&I. Try googling it; here is a start. http://www.foodrenegade.com/how-to-b...etosis-primer/