While on this subject, was just on vacation with part of that being on a cruise and the whole 3 weeks spent eating out and drinking more than normal. After 3 weeks of that, plus being off of my intermittent fasting and eliminating my one full fast day on Wednesdays during this time, I gained less than 10 lbs. Two days later, all but 2 lbs of that has come off.
At one point about a week ago I weighed myself and was within a pound or so of my pre-vacation weight, so it seems that, just like losing weight takes time, so can gaining weight, though the process of gaining weight usually tends to be much more fun ;-)
I will say that we were doing a LOT more walking than we usually did, with a couple days exceeding 25K steps. Either way, it just goes to show that your body seems to like to maintain an equilibrium and resist changes in weight.