It is generally accepted that those who overindulge in stilton and roast potatoes during December will want to diet come January. By the time the twelfth day rolls around most of us are feeling the effects of weeks of scarfing canapes and binge-eating mince pies compounded by excessive consumption of booze. Unless you're the sort of person who can shrug off any hangover and remains untroubled by an expanding waistline, you'll probably have had the D-word at the back of your mind for a while.

Don't do it. Or at least, if you feel the need to be healthier, don't go all out for one of the extreme diets or detoxes that abound at this time of year; instead try to ease yourself into something more balanced. I'm not anti diet (I have been dabbling with the eminently doable 5:2 this year) and I'm certainly not against healthy eating, I just think it's futile to start a strict weight-loss regime in January.

The main reason for this is the weather. We're in deepest, darkest winter. The cold and grey is relentless. We can go for weeks without seeing the sun. This is no time for asceticism: we need something to cheer us up. Even if you feel as though you've stored up enough body fat to see you through until spring, this is not the right time to deprive body and soul of fuel-rich comfort foods. Salads may taste wonderfully worthy, but on their own they are not enough to sustain. I have no taste for wheatgrass or alfalfa. I feed my family with healthy doses of stodge balanced with salads and greens (which are kept firmly on the side). Bring on the suet puddings, thick soups and curries, stews with dumplings, bean hotpots enriched with animal fats and some hefty cheese / carb combos.

Secondly, even if you are really careful about what you buy in December, the chances are you will be lucky enough to have leftovers. They're the best thing about Christmas and mine will last beyond January. This isn't just cold meats, pots of dripping and Christmas cake, but is also the result of the annual Waitrose New Year's Eve discount shopping scrum. My fridge ends up filled with pâté and terrine (bought for the earthenware ramekins) and potted stilton. No diet is worth giving up a January filled with tasty morsels on hot buttered toast.

Finally, there's the cost. January is a time when we need to tighten our belts in more ways than one. Most diets, apart from the dreadful cabbage soup diet, rely on a lot of very expensive ingredients, from the leaner types of protein to all those imported "health" foods. And this isn't just about the pocket – the same ingredients discourage nose to tail eating and actively encourage eating out of season, which may provide the palate with variety but does nothing for your carbon footprint. If there was a diet (the Nordic diet comes close) which focused on creating healthy, appealing dishes from our winter vegetables instead of depending on produce that is imported or comes from fuel-guzzling heated polytunnels, I'd almost be tempted to try it.

So I say we should leave the serious dieting to when the weather is warmer, diet–friendly produce is abundant and we're more likely to sustain it (the same applies to starting exercise). If you really must make new year's resolutions around food, be more realistic. There are plenty of things you can do: vow to use up all your leftovers, and cut down on meat and processed food. These, at least, you've a hope of keeping.