After the rout comes the purge. If we needed proof of society's increasingly disordered relationship with food, pleasure and health, it's in the screeching hand-brake turn from the gluttony of the festive season to the abject self-denial of the new year.
It never used to be this extreme. Oh sure, people might over-indulge during the Christmas feast, causing waistbands to feel tighter, and resolve to cut back a bit in January, eating more vegetables and fewer suet-studded puddings.
Now Christmas has become some kind of fetishized orgy of consumption in which people are encouraged to gorge themselves sick on smoked salmon, selection boxes and elaborately-pimped mince pies.
Then, come the new year, as they lie beached like bloated whales on the sofa, they are expected to renounce their greedy ways and throw themselves into a new kind of unhealthy obsession with food: how to eat much less of it, punish their bodies into submission, and get thin quick.
All of which is seriously screwed up, in my opinion.
This year, however, I notice that there is a crop of "alternative" diet books being flogged in the media. The theme of these books, some of which have been written by women who have grappled with their own issues around healthy eating, seems to be "the no-diet diet".
Rather than promising wonder cures, it's all about "fixing our relationship with food". Instead of whacking down the calories, they give sisterly advice on battling "food anxiety" - as in the soon-to-be-released tome How To Feel The Fear And Eat It Anyway.
And that sounds like a good thing, right?
Well, only up to a point. Because by doing all these earnest exercises to gauge and recalibrate your hunger levels, dutifully assigning numbers to exactly how ravenous you are at any given moment, aren't you still over-focusing on food as a problem to be fixed? And I'd argue that there are better things to do at the table than ponder whether your hunger is at 3 or 5 or 7 out of 10. Just forget all that and eat your nice dinner.
In The Diet Fix, the "obesity expert" and former anorexic Zoe Harcombe has lots of great advice about not calorie counting and not weighing yourself, and she lays into what she calls "the cruel lies" of the diet industry with gusto. Fair enough. But I'm less keen on Harcombe's mantra that food is fundamentally fuel. To the question "why do we eat?", she responds: "Because we need essential fats, proteins, minerals and vitamins. And then eating food that will give us those things."
Of course, food is fuel - like a car with no petrol, we wouldn't get too far without it - but culturally, historically, socially, it's so much more than that. Food is pleasure, it's a source of happy sustenance, an everyday delight and comfort, and any regimen that forgets that is erasing something that is essential to the human experience.
Self-denial and self-flagellation is a big part of the "new year, new you" message. Presumably this is why record numbers of people have signed up to the Veganuary movement, where you give up delicious, evil meat - and more - for the whole first month of the year.
Thousands of virtuous souls have already pledged their allegiance to the cause. Personally, I don't think I could stand a whole 31 days without butter. I mean, toasted Veda, with no butter? You've got to be kidding. I also need my cheese. And sausages.
Millions more are going down the more traditional route and cutting out alcohol for a month. But while denying yourself an evening glass of cabernet sauvignon might make you feel pure and wholesome, Dry January may not be as good for your health as you'd think.
Liver specialist Dr Mark Wright says that abstaining from drink for a month might actually act as a decoy, deluding people with potentially problematic habits into thinking they have a grip on their drinking.
He points out that: "Giving up alcohol for Dry January as some sort of detox is like maxing out your credit cards all year and thinking you can solve your financial problems by living like a hermit for a month."
Here's my advice, for what it's worth.
Don't waste your money on expensive diet or no-diet books that deal with barely suppressed fear about food.
Have the odd drink or two, if you fancy it. Cook delicious meals that you enjoy - and eat them.
Don't fret about any of it.
There you go: January sorted. You're welcome.