I did a brave thing on January 1 this year. I stepped onto the weighing scales. The horror that I had suspected - you often judge by the fit of your clothes - was confirmed. I'd gained a stone over the course of the previous 10 months. Aaargh!
The culprit was entirely obvious: the restrictions imposed by lockdowns and the reduction of movement because of the Covid pandemic. It wasn't my fault, surely, for sitting miserably in the kitchen, feeling sorry for myself and scoffing chocolate? Oh, no.
Anyway, everyone else I knew was in the same boat. We had almost all put on weight over the Covid year, with the annoying exception of my friend Marjorie, who remains a slender size 8 no matter what she eats. We all have one friend like this.
So, it's back to the weight-loss regime. By the time you get to a certain age, you usually come to understand what works best for your own body - and psychology.
Some people like to calorie-count. Some people like to join a group like Weight Watchers, or Slimming World - both are effective if you keep to the rules.
I've come to realise that what works for me is a variation on the now-fashionable regime of intermittent fasting.
There are lots of new diet books, apps and websites on fasting, and intermittent fasting - there are apps called DoFasting and Fasthabit Intermittent Fasting. Dave Asprey has just come out with a new book called Fast This Way.
The theory of fasting is both simple and historical: in past times, humans had to go hungry at various times of the year, because supplies of food ran out.
Our systems got accustomed to this obligatory fast and, when food wasn't available, the body just burned up its extra fat. Most religions have fasting periods, aligning reality with spirituality.
There are different ways of fasting and some people will prefer to follow a set regime via an app, or a book of meal plans, such as those authored by Dr Michael Mosley. I have friends who fast for two days a week, on the 5:2 rule.
But my own pattern is straightforward and without any special accessories: just eat nothing after 6pm. Nothing, bar a cup of herbal tea (always permitted).
A solid breakfast the following morning brings the fasting period to 14 hours. Uncomplicated and reliable. For me, this practice sheds a pound and a half - sometimes up to a kilo - per week.
On a social level, it's another instance of the present going back to the past. In my childhood, most people had their "tea" at about six o'clock in the evening. Sometimes it might be called "high tea", to distinguish it from "afternoon tea". In any case, it was the main evening meal. "Dinner" was at one o'clock in the day.
This accorded with the habits of the working man: he returned from his place of work (or, in agricultural circles, came in from the fields) at around 5pm and then had his "tea".
Only posh people had their "dinner" in the evening and there always were a few of those around. Some of the gentry continued to enjoy the multiple-course evening meals that had been the high point of Edwardian decadence.
And then, food habits began to change. The cookery writer Elizabeth David launched a culinary revolution in the 1960s by introducing every woman to French cooking.
Work habits altered. More women worked outside the home. "Dinner" in the middle of the day was fashionably replaced by "lunch". And the middle-class aspiration forthwith was to dine in the evening, at seven, or eight, or later.
Smart dinner parties were set at "7.30pm for 8pm", but sometimes you wouldn't get food until 9.30pm, by which time everyone was sloshed.
Holidays in Spain revealed that the Spanish ate their dinner at nine, 10 or even 11 o'clock at night. How chic.
But now, the food boffins tell us, eating late in the evening is deeply unhealthy. The older, more proletarian habit of having the last meal at six o'clock, is much better for the digestive system and for burning off the calories, too. And it can also be a route to the intermittent fasting of an effective diet.
Dieting, in the long run, has to accord with lifestyle. For some people, a relaxing meal at the end of the day with family and friends (or with those in your bubble, in present circumstances), accompanied by a few glasses of wine, is one of the pleasures of a civilised life.
My friend Marjorie is horrified at my spartan programme of no eating after 6pm: to her, the evening meal is the best moment of the day, having spent hours on business Zoom meetings.
Everyone is different. But the last meal at 6pm also leaves the rest of the evening free for other activities and I'm okay with that.
Fasting of one kind or another sheds the pounds, but all diets require discipline, naturally.
During the Covid year, I just couldn't be bothered with the discipline and I know a lot of people felt the same, as in "What's the point? I'm not going anywhere."
But spring is on the way, days are visibly brightening and this is the time to shift that extra lard acquired in the months of despond.