Weight loss

So I've been stuck at the same weight for a few months now.  It's a little frustrating, especially now that I can run more than 10 miles, and with my bike rides included, I burn lots and lots of calories every week.  But no change.  I tried giving up soda on March 1st.  I did really good for a few weeks, now I'm back on.  I decided to go back to soda because when I was off of it I was pigging out on everything else: donuts, licorice, candy bars, fast food.  And my weight went up.  So back on the soda and my weight leveled off.  Yesterday morning I hit a weight I never thought I would see again: 208.  I was shocked and dumbfounded.  I'm not sure what reminded me, but I realized I hadn't been drinking enough water.  So yesterday I drank a lot, at least 100 ounces.  And today close to the same.  And my eating habits have stayed about the same.  And this morning I weighed 205.  Huh?  3 pounds lost in one day?  How can that be?  I also weighed myself tonight after my run, and chugging 20 ounces of water.  203.  Huh?  So here's what I've concluded.  When I don't drink enough, I retain water.  These kind of weight changes can only be due to fluids.  I think my body has been in preservation mode because I wasn't drinking enough water.  And now that I'm hydrating, it's not retaining water any more.  I also read an article today about how when you are dehydrated, your kidneys don't function properly.  So your liver does their work removing toxins from the body, and doesn't have the additional capacity to metabolize fat.  So here's my conclusion:  Drink lots of water, let my kidneys run at maximum capacity, and hopefully my liver kicks in like crazy and metabolizes lots of fat.  We'll see how it goes.  Sound like a good plan?