I went to a buffet recently and I managed to enjoy myself while not going overboard. You should enjoy yourself too!
Here's what I did:
- Ate very lightly during the day, but filling things.
- drank lots of water
- I stuck to steamed seafood and grilled things. All very yummy and very nutritious. I had quite a bit of snow crab legs because I LOVE them and they are also very low in calories
- fruit for dessert!
You might also want to just eat at your maintenance level rather than trying to stick to your losing level. Have fun, get back on track the next day and don't sweat it.