It happens to the best of us.

You've a fab outfit bought in advance for a Christmas or New Year's party but when the time actually rolls around, it just won't fit. It's no cause for drama though - there's nothing wrong with some festive indulgence. If you think you're going to make it through Christmas without spending at least three days on the couch clearing out a tub of Celebrations and a selection box or two, you're fooling only yourself. That said, if you do want to get to January without completely doing the dog on it, one personal trainer has shared his tip to avoid gaining a spare tyre. PT Max Lowery says working out on the days when you've a party or you know you'll be eating a lot can help get your metabolism running and offset the damage you'll do later. "On the days I’m exercising and indulging I can let my hair down and enjoy what’s on offer, but on the days that I’m not indulging so much, I aim to eat more healthy fats and protein, and less carbohydrates – especially processed carbohydrates like bread, pasta, crisps, biscuits and milk chocolate," he told Get The Gloss. Planning your meals around your social outings can also help. "Filling up on healthy fats and proteins before you go out to a Christmas party can be a great way of keeping things in check and making sure you’re not ravenous when you arrive," added Max, whose celebrity followers reportedly include a number of Victoria's Secret models. "I like boiled eggs, salmon fillets or avocado." Or you could totally cut loose and just let future-you deal with the consequences. It is Christmas after all.