Again, you probably won't gain weight after one huge holiday meal. But you probably will gain weight if you decide to just eat whatever you want between now and New Years because wtf 'tis the season. "Two months of poor eating is a hell of a lot harder to fix than a couple of days," says Langer.
So don't adopt an all-or-nothing attitude. Instead, just try to stick with mostly whole, unprocessed, good-for-you foods the majority of the time, and then don't worry about eating the biggest piece of cheesecake and half that plate of brie at the holiday party.
"It's just a matter of eating what you like and getting over it, staying active, and knowing that the next day you have to go back to your regular eating habits," says Langer.