For most of us, it's day seven of the diet. You know, the big, life-changing one where you vow to quit sugar/drop three dress sizes/excavate your abdominals. This year will be different, you tell yourself. It has to be. And yet by the time February 1st rolls around, you've succumbed to the Mini Eggs, the two-for-one Pinot Grigio and the packet of Percy Pigs that were winking at you in the self-service queue at M&S.
But here's a thought. Don't diet. Not now. January is dark. It's too cold to lug yourself round the park in your shorts and T-shirt. Only the blandest fruit and vegetables are in season and besides, you're scientifically hard-wired to fail.
In a recent study by the University of Adelaide, scientists, along with their phalanx of little mice, found out some interesting stuff. Turns out that after a heavy period of binge eating (also known as Christmas) the nerves in your poor stomach become desensitised. Translation: you need to eat more to feel satisfied.
That's why January can seem so hard. How are kale chips and flax crackers going to cut it when you've been used to third helpings of Heston's Christmas pudding for the past 10 days?
The answer then is to add things into your diet, not take them away. I call it 'transitional' eating. Sure, go for your life with green juices. But also make sure your dinner is a thick stew rather than a quinoa salad. Make small, barely noticeable swaps. I'm ditching agave (too high in fructose) for rice vinegar, and home-made jam on toast for mashed avocado and olive oil on rye bread. If I want a glass of wine I make it red and use a smaller glass. As for tea (and I was a five cups a day caffeine hoover) I have ditched it for Teapigs' lovely licorice tea, that tastes like a handful of bonbons.
They say it takes 21 days for a habit to stick. I'd say double that to be on the safe side. And I don't know about you but the thought of 42 days of deprivation would fill me with about as much dread as the clearance racks at TK Maxx. It'll also do all sorts of nasty things to your metabolism, suddenly slashing your calorie intake like that, meaning ultimately it's even harder to shift weight.
So do yourself a favour. Don't start the diet now. Instead, eat up. Just maybe not with another portion of Heston's Christmas pudding.
Farrah Storr is the editor of Women's Health UK, January/February issue on sale now