What you don't know about sodium depletion and potassium loading
I see that most people on here seem to think that cutting out sodium and raising potassium to ridiculously high levels is the best way to shed excess water. Not only can this process be dangerous (even fatal if grossly overdone) it is not that effective. You see, in terms of ADH (anti-diuretic hormone) decreasing sodium intake will reduce ADH output. However, your water and ion levels are controlled by several hormones, not just one. Think about it, your body doesn't want to lose alot of water. Why? B/c an increased urine volume means decreased blood volume, decreased blood volume means decreased blood pressure; which is dangerous in the short term as it decreases the amount of blood to and from the heart.
so if you lower your sodium and increase your potassium, the body will fight water loss... how does it do this????? By increasing aldosterone. Aldosterone is member of the steroid hormone family and it's production is stimulated by EITHER an increase in blood concentrations of potassium or a decrease in concentrations of sodium. Just wait, it gets better... aldosterone attaches to receptors on the distal tubule and on the collecting duct (part of the nephron... the functional unit of the kidney) and causes water to be reabsorbed into the interstitial fluid. So instead of excreting this water via urination, your body will retain it to increase your blood volume and return your blood pressure to normal.
Just goes to show you that you can't fool your body, it is a lot smarter than you are... that's what millions of years of evolution will do for you.
Your best strategy for losing water (if you don't want to take illicit drugs) is to use a moderate approach. Sodium loading isn't a bad idea starting about 10-15 days out, but when you deplete don't take it to ridiculously low levels... stay within 1-2g per day. By the same token don't load on a bunch of potassium, eat the amount of potassium you normally would.
-Layne