i'm pretty liberal with salt and butter on steamed vegetables, so my guess is that the day before i just OD'ed on sodium which made me retain a few more pints of water the next day. it wasn't an anomaly... i recall later in the day i was reading 175, but overnight it just seemed to disappear. just trying to point out that if you only weigh yourself once a week and you hit a bad day, it could be very discouraging.
when i was dropping weight, i recorded 3-4 weigh-ins/ day. some up, some down, but it was so easy to see the general downward trend over the period of a week or a month.
currently i'm sure the 168/ 169 readings are the more accurate. for anyone trying to lose weight who is already recording a healthy BMI, good luck with that. after hitting 24, not that i'm pushing the envelope, but i'm barely seeing 1-2 lbs / month now, but, hey... anything down beats anything up.