This time of year, people watching their weight while facing down holiday parties can be particularly susceptible to scaremongering by the fat police. You know the type: the guests who spoil the party by rattling off the calorie counts in the gingerbread men and stare you down as you reach for the eggnog.

Unfortunately for everyone else, many of those spoilsports have found work in the country’s public health industry, earning their living by professionally shaming those who ever indulge. Groups like the Center for Science in the Public Interest have made careers out of being food Grinches. With holiday fare on the menu, there’s plenty of merriment around to steal.

Last Christmas, CSPI filed a complaint against several beer companies, accusing them of using Santa to promote "binge drinking events” — in reality, a series of pub crawls hosted by St. Nick impersonators to raise money for charity. And before Thanksgiving last year, People for the Ethical Treatment of Animals spread the lie that "turkey consumption might kill you,” based on the fat content in a roasted bird.

But there’s no reason to believe Christmas dinner will leave you as rotund as Santa Claus.

The key to maintaining a healthy weight is moderation, and a once-a-year celebration defines moderation. A tradition of sharing mugs of hot buttered rum on Christmas Eve is not going to cause your waistline to balloon. Just like one virtuous salad never made anyone thin, one hot toddy never made anyone fat.

Contrary to what the food-guilt brigade says, it’s easier than ever to keep a handle on your calories in versus calories out. Last month, The Associated Press compared the 1956 edition of the Better Homes and Gardens cookbook with the 2006 version and found that holiday recipes have actually gotten healthier over time. More dishes called for the use of lower-calorie ingredients and portion sizes are trending smaller as well.

And study after study underscores the importance of physical activity in weight control. As the Center for Consumer Freedom explored in our report "Small Choices, Big Bodies,” physical exertion on the job and at home has been on the decline for decades, contributing dramatically to the nationwide weight gain — more so than any change in what or how much we eat.

This is a problem with a solution that doesn’t involve holiday dessert deprivation. For those who welcome the first snowfall, winter sports abound: skiing, sledding, ice skating and snowshoeing are all fun calorie burners. And health clubs typically offer special rates for new members around New Year’s Day.

So go ahead and savor the Hanukkah latkes and Christmas cookies that make the season special. "Christmas comes but once a year,” as the carol goes. Don’t listen to anyone who tells you not to enjoy it.