After the feast, the famine. On TV, we've had a month of twinkly, bloated decadence: ad after ad has been replete with scenes of joyous gluttony; families coming together and breaking bread (and every other carb) in the name of festive goodwill.
Watch enough of these ads, and you start to think that brandy butter is a food group, and forget that salad even exists.
And just as night follows day, the cheery, chummy Christmas ad has been supplanted by - dun-dun-dunnnnnn - the January ads of contrition. And what a shock to the system these are.
These are the January ads for slimming aids, gyms and Gaviscon that 'helpfully' remind you that you went way, way overboard during Christmas. They're the screen equivalent of two brisk slaps on the wrist.
You've spent December working on that spare tyre, and now is the moment of reckoning and reprimand. They're like an unkind, meddlesome aunt, intoning: "Time to get rid of all that nasty, gross blubber - ideally, in the first two weeks of January, if you can manage it."
Add the bottom-feeder celebrities who were photographed looking a little wobbly beachside in August but have returned to a size 6 thanks to a certain DVD workout, and January starts to feel a lot longer than its allotted 31 days.
I used to watch these ads, and pore over the 'New Year, New You' supplements, with a mix of gritted determination and guilt. I'd cower from the bossy tone of January's media output, agreeing that, yes, Christmas was a calorific moment of madness.
The problem with January's 'New Year, New You' message is that it hammers home the idea that being overweight is a moral failure, and one that you need to spend significant time, money and energy on if you want to reach your true potential as a functional human being.
Basically, you lack discipline, self-regulation and a whole host of other functional human qualities, which is how you got yourself into this mess.
The other problem with the glut of media messages is that they insinuate that there's no way you can get anywhere without their help. They hammer home that weight loss is difficult, torturous and rarely enjoyable.
And it is all of those things.
They hint that, whatever your intentions, you'll fall at the first hurdle because you didn't sign up to whatever fad diet, hybrid workout or mad gadget they're espousing.
It's why so many people pin their hopes of dieting success on an extraneous element - like a Nutribullet or a Bikram class. And why so many people, ultimately, will fail in their January slimming efforts.
I've said it before and it bears repeating: the diet industry is not your friend. The diet industry wants you to fail, as it is designed to encourage repeat business (I make a distinction between weight loss and wellness here, as many wellbeing disciples would rather see you at a size 14 and happy and fit).
Above all, they don't take into account the sheer Byzantine complexity of obesity. There are dozens of reasons - psychological, economic, developmental, physical, cultural, genetic - that may explain why a person is overweight, or why they can't or won't engage in self-care. Reasons, incidentally, that your typical Dukan/Atkins peddler knows nothing about, and cares little for.
I grew up in the 80s, for instance, where microwave ready meals and boil-in-the-bag stuff were seen as truly cosmopolitan: the proper, sensible choice of the busy working parent.
My mother worked outside the home and we inhaled the stuff as kids. It took years of learning about fresh foods after I left home and undoing the habit of a lifetime for changes to happen. And that's just one element in my life that has seen the scales tip the 'wrong' way.
Fine; at its core, extra weight has to do with eating too much and not moving enough. But those who reckon that eating less and moving more will sort one's weight issues out are woefully misguided. And this simple tenet is doing us all a disservice.
An expert I interviewed recently has a theory that being healthy (and by extension, losing weight) is easier than we make it out to be.
"It's a question of putting down the Twixes when you pick them up in Aldi, like you'd make a child do, and then making one small decision after another. This will take tiny, repeated efforts. Decide to go for a walk or not. Decide to eat well or not. But make the decision and move on from it."
He has a point, but things are rarely that simple.
We are moving in the right direction: Women's Health magazine editor Amy Keller Laird announced this year that she is banning the phrases 'bikini body' and 'drop two dress sizes' from her covers.
This year, I've decided to give the media flogging of the perfect body a wide berth. For now, I'm pretty much okay with my less-than-ideal weight. This may change soon; this may not.
But right now, eating a whole head of broccoli for breakfast holds no appeal. And I suspect that more and more women are getting really bored with being told what is an acceptable size for their bodies.
We're realising that dieting, and staying as close to that feminine ideal, is not a requisite to being a normal, grown-up woman.
Forget looking 'beach ready': if you feel good and your body enables you to do what you want to do with your life - to see more, do more, get to more places - surely that's goal enough?