A great take-away message from the article SK posted:

"Barring any medical conditions such as thyroid imbalances or medication side effects, by exercising regularly and eating a healthy diet based on whole grains, fruits, vegetables and lean proteins, it’s normal to fluctuate within a 10-pound weight range. But to determine how healthy you are, keep track of your energy levels, how well you are performing athletically, and periodically check your standard health markers with your physician. That way, the numbers on the scale won’t matter as much."

Now, I take issue with the 10-lb weight fluctuation mentioned in the article; I personally consider a 2-lb weight fluctuation to be completly normal. But apart from quibbling with the actual number, this makes great sense to me.

It saddens me when people fret over a 0.5 to 1 lb weight gain. I think the body goes thru readjustments, and sometimes body weight will bounce around a bit, it's perfectly normal, imho. Probably has as much to to with your last trip to the bathroom as anything.