Just as Christmas is traditionally a time of such excess that by the end of it all you can do is lie on the sofa grunting, swollen and red, like a human-sized pig in a blanket, the dawn of a new year is almost universally viewed as a time for self-improvement. Whether it's dieting, ditching fags and booze, or committing to that fluffiest of notions of "being a better person", 1 January (OK, 2 January, because only the truly masochistic commences a diet or gives up smoking when they're apocalyptically hungover) acts as a natural starting point for the turning over of a new leaf. I realise that, much like those people who shop online on Christmas Day – 30% of us, according to Barclaycard – discussing dieting and abstinence before New Year's Eve is seen by many as sacrilege.
For anything goes during this strange, inter-pour period between the 25 and 31 December. And as I have a carefully curated cheeseboard waiting, it pains me to have to invoke the phrase "obesity crisis" at this juncture. But the truth is that weight will have been on many people's minds as they stuff themselves with sausage meat in preparation for whatever detox or cleanse is fashionable this year.
Come January, Brits on the Six Weeks to OMG: Get Skinnier Than All Your Friends' diet will be plunging themselves into cold baths and blowing up balloons to exercise their abs. Meanwhile, those on Beyoncé's preferred Master Cleanse diet will be ingesting nothing but a funky-tasting "lemonade" comprised of lemons, maple syrup and cayenne pepper. All those poor, miserable sods on the 5:2 will be snapping horribly at their friends and relatives while trying to take the short trip between their desk and the miso soup place without falling over. Those on juice diets will be on the toilet.
Everything, in other words, is nothing if not extreme. The myth of self-improvement makes it thus. It's commonly stated that many diets fail for this very reason: they set unrealistic goals that are impossible to stick to. Even Beyoncé, a woman who once described herself as "a natural fat person dying to get out", has a "cheat day", yet there are those who persist in the face of the accepted scientific wisdom of "eat less, move more" by attempting the kind of punishing regimes that not only make them miserable but enrage and frustrate those around them (please, stop tweeting about your colon cleanse).
In this world, where it's either supersize or superskinny, there is no longer any middle ground, as a website's mock-up of a "plus-size Barbie" illustrated this week when the designer gave her a quadruple chin. It's the toy equivalent of watching Gwyneth Paltrow in Shallow Hal. Either you have a doll so extremely proportioned that she can't stand up without toppling forwards, or one that looks like a Barbie in a comedy fat suit. Either you look like you've made the auditions for the new series of My 600-lb Life, or you're looking "pale, drawn and dangerously thin".
This is especially true of women, but is also increasingly becoming the case with men. Looking at certain corners of the media will have you wondering where all the normal-sized people with normal appetites are, a phenomenon that I suspect partially accounts for Jennifer Lawrence's popularity as the only actress who is brutally honest about what she eats. Ordering McDonald's from the red carpet because the supposedly obligatory pre-awards ceremony fasting was too much to bear is an act that is guaranteed to endear you to a generation of hungry women.
I know I'm not the first to preach moderation, but as the dieting industry gears up to bombard us with propaganda, it's important to remember that sometimes the phrase "cold turkey" is best employed where it belongs: Boxing Day morning, end of. Whatever form they take, extreme self-improvement measures are frequently destined to fail, and are guaranteed to get people's backs up.
They are also vulnerable to sabotage. Sit in the pub and say you're giving up smoking and it's only a matter of minutes before someone waves a ciggie in your face. Go to a party and say you're not drinking and people will demand to know why, even if the answer is more information than they bargained for ("Antibiotics," she responded. "I've got chlamydia."). Some people's loved ones discourage them from losing weight, and can even enable their bad habits. It's a phenomenon tackled hilariously in the John Cooper Clarke poem Get Back on Drugs, You Fat Fuck.
It's why I have come to believe that self-improvement is best conducted temperately and on the sly. Not only is a cycle of bingeing and gorging doomed to fail, but it's spectacularly easy for other people to comment on. Now, back to that cheeseboard.