Friday, I went to spend a few days at a cabin on a lake.
During those few days I didn't really track anything except my morning coffee, so I'd keep my streak and have something in my diary. The rest of the time? I just ate. A lot. Hot dogs, s'mores, pizza, hamburgers, a whole bag of chips + container of dip, candy, an entire bottle of wine - loosely estimated and averaged, probably about 4,000 calories a day, for 3 days.
I was definitely more active while we were there, but not enough to account for more than twice my maintenance calories - nowhere near, to be honest.
I did nothing but get back to my usual calories when I got back - and less than usual exercise the first day because I was tired.
I knew it was coming up, so I did an 'Ann Experiment'.
Friday morning (pre trip) - 130.1
Monday afternoon when I returned - 132.6
Tuesday - 131.7
Wednesday - 131.7
Thursday (today) - 130.1
A day or even few being off your usual plan - and subject aside I won't call them bad days, because for me they were EXCELLENT days - isn't going to ruin you. It isn't the end of the world. It isn't a big deal.
I'd encourage almost anyone to do this sort of experiment if they can take the initial jump on the scale. Largely because I think it's a good weapon against 'all or nothing' thinking - ie: I ate more than I intended/wanted for a day or two, everything's ruined forever now. KNOWING what happens - in general but also for YOU - is powerful.