Stay hungry all the time. IMO, you are at the stage where it is about how much hunger can you tolerate to achieve your goal. IMO, you are fighting your homeostasis which is why the math does not seem to work. Ask yourself this question before you eat anything - will eating this make me faster or slower.

You can see how easy it is to become anorexic. The thinking and discipline to lose those last few pounds is not healthy physically or mentally but it will make you faster.