From what I understand about metabolites (these are what you're getting tested for, not actual THC), they're going to be in your body for a good while if you're a daily smoker. There's not really a way to get rid of them because your body will keep making them for a while even after you stop smoking, much like your immune system does with antibodies. That being said, dilution is just that: diluting the metabolites that WILL be there enough that they're either undetectable or under the red-flag threshold. Putting my 2 years of biology to work here, that means the best way to mask them would be to shoot your metabolism through the roof in the weeks leading up to the test (eat 5 small meals, drink lots of water, exercise first thing in the morning and little bits during the day, etc.), and then 3 or 4 days before the test you want to completely reverse this and send your body into energy-save mode. Hyping it up will rid you of lots of the metabolites but, if you're not clean for about a month, you want to slow it back down right before the test so that the remaining metabolites have a hard time leaving your fat and blood and making its way into your urine. As far as high or low fat diet I can't really comment on this because I simply don't know, but I do know during the ramp-up you want a lot of lean, easily metabolized energy (stay away from starches) and then during the slowdown you will want to eat maybe one meal a day if you can handle that, composed of lots of sugar and starches. I will say I have never tested this as far as a urinalysis and I'm sure someone will correct a point or two i've made, but I do know this method will seriously affect your metabolism (been working out for years and I cycle this way to bulk/cut). Good luck and let us know how it turns out!