The festive weeks between Thanksgiving and New Year’s always provide plenty of reasons to push dieting plans aside until it’s time to make resolutions. But with obesity rates rising, anti-fat activists have gotten increasingly cheerless in their calls for slimming down. Even Santa hasn’t been spared.

Last winter Australian researchers writing in the British Medical Journal lambasted Santa as a bad role model for being fat. Former U.S. Surgeon General Steven Galson warned just a few years ago that “Santa is no different” when it comes to setting a good example.

These sullenly portray obesity as a naughty-and-nice issue that requires society to demonize St. Nick. Carrot sticks, good. Fat Santa, bad. Candy canes, bad. Egg nog, Christmas cookies and hot chocolate. Bad, bad, bad. And so on.

Just in time for Christmas, though, one hot toy this season joins the fight against obesity in a jolly way: interactive video games. Released in November, the Xbox Kinect gaming device features cameras that require and track movements. It’s the latest move by video game systems to increase interaction with digital workout buddies by playing games — notably begun by the Nintendo Wii’s motion-sensitive console in 2006. Not to be outdone by its competitors, Sony released a motion-based controller in September for its PlayStation 3 platform.

I am not writing this to shill for Microsoft, Nintendo, or Sony. But as technology advances, black-and-white notions of good and bad in the obesity epidemic are quickly melting away.

It may seem strange that playing video games can be an obesity prophylactic. But some have had success. Researchers from the U.K. discovered that kids burned 150 calories per hour playing Wii games. (That’s 156 percent more energy than if kids spent an hour on Facebook.)

There are increasing opportunities for kids of all ages to stay fit and active while having fun — without having to blacklist pie or engage in finger pointing, which burns very few calories.

In fact, more and more research is finding that it’s staying active — not avoiding every Christmas cookie that comes your way — that’s the key to a healthy lifestyle.

A 2007 study in the Journal of the American Medical Association determined that physical activity levels, regardless of weight, determine longevity. Another study found that individuals who forgo regular exercise age prematurely.

Perhaps Santa — climbing chimneys and hauling bags of presents — is just such a role model for the “fit and fat” community.

The key is moderation. A gingerbread man will do no harm after swinging your arms in a few games of virtual tennis. We should encourage healthy behavior, but that doesn’t involve converting “Santa” into “Satan.”

Let’s hope this Christmas season is a merry one for all — even the killjoys. Santa doesn’t have to give them coal for their Grinch-like behavior, even if they only leave out water and lentils for him.