My experience: in the first 2 months of working out, this happens about 80-90% of the time after a really hard workout. Thereafter, only about 30% of the time - I think in my case my body just decided to hold onto the excess water in a semi-permanent way so the fluctuations aren't as noticeable. And then if I stop working out for a week, I drop 3-4 lbs without doing anything differently, but it doesn't really show up visibly or in my clothes.
For it to be visible in the mirror, I would think your body fat would have to be pretty low like under 18%.
Edited by: NAUSIKAA at: 2/21/2013 (06:33)