The silly season can be the downfall of many a dieter, with boozy parties and fatty festive food all but ruining the abstemious existence of the past 12 months.
But it doesn't have to be that way. Common sense and a few top tips from experts will get you through Christmas with your figure intact.
Nutritionist Sarah Hanrahan says there's no point trying to diet at Christmas time, so give up any hope of fitting into a swimsuit in January that was too small in December.
"Trying to diet through Christmas is almost impossible unless you've got iron willpower," says Hanrahan, of the New Zealand Nutrition Foundation. "People get so depressed when it doesn't work, but if they can get over that whole thing about feeling bad about what they eat at Christmas and just enjoy appropriate-sized portions, they'll pop out the other end ready to get on with it, rather than setting themselves back by gaining weight or fighting a losing battle to lose weight."
Avoiding the fat trap is about common sense, says Hanrahan.
Parties can be a minefield of fattening nibbles and calorie-laden booze, but Hanrahan advises having a healthy snack at home before you go.
"If you arrive with food your focus, you'll have half a dozen sausage rolls before you realise it," she says. Making an effort to mix and mingle is also a good way to avoid diving into the snacks, she says.
Booze is often a pitfall and is hard to avoid during the festive season. "You can easily knock back drinks without thinking about it," says Hanrahan.
Unfortunately, most of our favourite alcoholic drinks are laden with calories. Hanrahan suggests diluting drinks, such as adding soda to wine to make a spritzer, opting for diet mixers or ensuring you alternate each glass of wine with a glass of water.
When it comes to the traditional Christmas dinner, don't deprive yourself, but don't go crazy.
Make sure half your plate is vegetables and load up on berries for dessert.
Moderation is the key. "Don't go without," says Hanrahan. "The worst thing to do is cut yourself off from everything around you. Then you'll just really resent it and ultimately you won't succeed."
Personal trainer Scott Wadham agrees. Load up as much as you can on salads, and take small pieces of everything so you don't feel like you're missing out. Wadham, of Auckland gym Corpo Bello, says in mid-January he is inundated with people wanting to lose their Christmas flab.
But the festive season is no excuse for letting exercise habits slip, especially if the summer weather holds up.
"I always tell people that if they are going to indulge, do the groundwork before," says Wadham. "Go for a big run and give yourself some credits, or burn it off afterwards."
Exercise should be incorporated into your holiday as part of the family fun, rather than avoided or seen as a chore. "Anything that gets you puffing is great - a game of touch on the beach, throwing the frisbee around, mowing the lawns, going for a swim. Whatever it takes to get your heart rate up."
Dietitian Angela Berrill suggests starting Christmas Day with a bout of exercise and a good breakfast. "It's good to go into Christmas lunch hungry, but if you are ravenous you'll end up gorging yourself," she says.
Dietitian Sarah Ley says traditional Christmas foods are designed to be eaten in cold weather and have a high energy value. One option is to ditch them in favour of lower-energy summer foods like salads and cold fruit desserts.
If all else fails, physically distance yourself from high-fat treats, says Berrill. "If you're a picker, it's best to stay on the other side of the room from the chocolates and nuts."
All our experts agree that changing day-to-day eating habits should be the focus, not a once-a-year festive blow-out.
Hanrahan says "enjoy Christmas for what it is. The reason people are overweight is because of their everyday habits, not because of a week over Christmas."
Get back in shape
Alex Flint, 31, is like everyone else. He too gets tempted by glazed ham and the mountains of pavlova abundant at Christmas.
However, as a personal trainer at the Netfit Training Room in Ellerslie, his self-control is better than most.
For those wanting to get rid of their festive fat, the gym offers boot-camp style training.
"Basically we do a lot of different types of fitness training . We do boxing, use kettle bells, skipping, a lot of running and play a lot of tag based running games."
The combination of cardio and weightlifting has some huge results, says Flint.
"Some of the girls have lost incredible amounts of weight. When they started they'd never done any exercise. Now they've lost almost 20kg."
Another novel way to lose weight is through the modified strongman training program.
"You basically run and throw things around."
Different types of training often help people stay committed as they don't think of it as hard work.
While many join gyms in the New Year saying they will get in shape, doing circuit training with friends and family makes it more likely you will continue.
Avoiding the trap
* Don't diet at Christmas
* Eat regular meals with lots of veges
* Don't go to parties hungry
* Mix and mingle
* Think about your drinks
* Eat small portions
* Cut fat and skin off fowl
* Eat slowly
* Exercise on Christmas day