As another summer approaches, I’ve embarked on yet another attempt to lose weight. You’d have thought I’d have learnt my lesson by now – what goes down, must come up – but it turns out yo-yo dieting is actually good for you. At least, that’s the conclusion of a team of researchers at Oxford University who analysed 124 trials involving 50,000 people trying to lose weight. They lost an average of between five and ten pounds and regained it at a rate of less than a pound a year. According to Professor Susan Jebb, co-author of the study, it took the participants in the study between five and 14 years to put the weight back on, during which time their blood pressure, blood glucose and cholesterol levels were all lower, thereby reducing their risk of diabetes and heart disease.

The last time I lost weight was when I got cancelled at the beginning of 2018. This followed my appointment to the Office for Students, a new government regulator. Within minutes of it being announced, an army of online metal-detectorists set to work, frantically sifting through everything I’d ever said or written trying to find things to be offended by. Needless to say, they soon struck gold and within days a petition demanding the prime minister sack me had attracted more than 220,000 signatures. It was the usual story: Downing Street first stood firm, then wobbled, then a trusted intermediary called and urged me to do the decent thing. I duly resigned and issued a grovelling apology, whereupon the same mob demanded I stand down from every other job I held. Within a few weeks I had lost five positions. But there was a silver lining. I also shed half a stone, which I referred to at the time as ‘the public humiliation diet’.

I went on to lose another stone and managed to keep it off until March 2020, when Boris Johnson gave the British people a very simple instruction: ‘You must stay at home.’ Unlike him, I took this literally and the upshot was that 16 months later, when ‘freedom day’ was declared, I was back up to 12 stone. So I’ve given myself the task of losing 21 pounds again. Five years ago, I had the advantage of plenty of leisure time and was able to work out every day. This time round, the only exercise I get is walking to and from the Tube instead of taking a Lime bike. Consequently, in order to lose a comparable amount of weight I must limit myself to 1,500 calories a day, which is incredibly hard, particularly if you’re an epicurean like me.

To make it easier, I try to avoid eating anything between 9 p.m. and 1 p.m. the following day. You get used to that, believe it or not, but it does mean I drink half a dozen flat whites every morning – not for the caffeine, but the full fat milk. For lunch, I try to limit myself to soup – a pot of Sainsbury’s carrot and coriander is less than 200 calories – and for supper a piece of fish and a salad, although the temptation to include all sorts of verboten ingredients in the salad – gherkins, sun-dried tomatoes, vintage cheddar – is often overwhelming. I also don’t drink on three nights a week, using the NHS app Drink Free Days to monitor it.

Losing the first seven pounds wasn’t hard, but losing the next was murderously difficult. There were days when I did 20,000 steps and consumed less than 1,000 calories and would weigh exactly the same the following morning. On other days, I would slip up – drink a little too much at a dinner party and give myself permission to tuck into the cheese and then have a large helping of pudding – and the next morning I had gained four pounds. But I have now lost a stone and the next seven pounds are in my sights.

One of the big motivations for me was seeing if I could get below the weight of my two eldest sons, Ludo and Fred. They’re both fit, fully grown teenagers, although slightly taller than me, and we all use the same electronic scale, which keeps a log of our different weights. I got a huge sense of reward last week when I stepped on the scale and was asked to indicate who I was: Toby, Ludo or Fred? In other words, my weight was now very close to theirs. When I bragged about this they ridiculed me mercilessly, pointing out that muscle weighs a lot more than fat and showing me their biceps, but I retorted that remaining slim when you’re a young man is easy. (According to the health survey for England, only 8 per cent of 16- to 24-year-olds are obese.) If they weigh the same as me when they’re 59, then I’ll be impressed.

When I’m down to ten-and-a-half stone, I’m determined not to put it all back on as quickly as I did last time. Not locking down again, for whatever reason, would be a big help.