I’m disappointed with my performance in this so-called diet. In football parlance, I just didn’t turn up. It was the proverbial wet Wednesday night at Ewood Park, rain lashing down, thousands of baying Lancastrians, and I went missing, never showed for the ball, barely got a kick, wasn’t up for it. They should pay you to watch me.

Yes, I think I might be one of those fair-weather, Fancy Dan dieters, quite possibly Mediterranean in origin and probably wearing poncey silver boots. I’m a disgrace to the shirt, or rather, I would be if I could get into the shirt. Whenever it got a bit physical, a bit tasty, I didn’t fancy it. Or rather, whenever it got a bit tasty, I ate it.

I set out to lose 20lb and I lost ten. And I only achieved that with some questionable dehydration tactics of the sort that land boxers and models in hospital. People are trying to console me, saying 10lb in four weeks is pretty good, but I know how hard I tried, and it wasn’t hard enough. I haven’t got much time for Boris Johnson, but I admire the way he gave up booze for three months to get his head together for the mayoral campaign. Three months; I couldn’t manage one.

My main excuse is travel. Unluckily, during the four-week period, I had to be in Spain for four days, France and Sweden for two each, plus there were a couple of weekends in Kent. Travel wrecks routine, and thus it is the implacable enemy of weight loss, because weight loss is all about grinding, repetitive routine. And travel creates low-level anxiety, too – anxiety I tend to allay with fattening snacks.

Each trip had its pitfalls. I happen to be very fond of Scandinavian food. No problem with meatballs, herring or brown bread, but I don’t think fried potatoes, fruit pies and cheese sandwiches for breakfast are classically slimming foodstuffs. I’m also fond of Spanish food, and Spanish wine, and Spanish beer, and I instantly adopted the Spanish habit of stuffing my face into the small hours and then sleeping until noon, which can’t do your metabolism any good.

In France I ate three five-course meals in the space of 24 hours and the most expensive one cost 15 euros. People say that eating out in Britain has caught up with eating out in France and perhaps at very high-end restaurants that’s true. Otherwise, it’s obvious nonsense, and I took full advantage of the discrepancy. I had a cream tea in Kent, too.

At bottom though, the failure has been a failure of will. It’s a dull old business, losing weight, a negative business: not doing this, not going there, saying no, shrinking into your shell. I’ve usually been able to do that when required. If anything, refusal, withdrawal and abstention were words that described my default state. But as I get older, I find I don’t want to live like that. Not for the sake of an inch or two on my waistline anyway. Maybe it’s just laziness, resignation to the inevitable, but I’d like to think, excuse the pun, that I’m becoming a more rounded character.

I see these men, sometimes women but usually men, cycling or running to work on the towpath – sinewy, psychotic gleam in their eye, so fit even their faces are fit, noses, ears, the lot. And they’ve got their heart-rate monitor on, and you can see they’re up against some unforgiving personal clock. While I admire their physical vitality, I also think that perhaps other aspects of their potential or personality are dead or dying. Certainly, they can be selfish, these men. They don’t slow down for anyone, not for me, the mum with the pushchair, the teenagers canoodling under the bridge, the lame old man walking his dog. I’ve seen one or two near misses, one or two heated exchanges.

Ah well, I suppose this would have all been a bit of a giggle, this diet, your typical Beta Male tale of mediocrity, and yet the charity aspect means I can’t laugh it off. Paul Hayes, a big boss here at News International, had offered £100 for charity for every pound I lost, £250 per pound if I shed the full 20. So I could have raised £5,000 and I actually raised £1,000. Which is, of course, a decent amount of money, but not as much as it could have been.

Two days before my diet deadline, and about 20 yards from my home in Hackney, a teenage boy was shot by (apparently) another teenage boy at five in the afternoon. A gang encroaches on to some other gang’s patch, insufficient respect is shown, an argument develops, one boy pulls the trigger, another boy lies bleeding all over the path, right next to a playground full of children, some of them not much younger than him.

The charity I nominated is called Chance UK (www.chanceuk.org), which supplies adult mentors to youngsters – boys mostly, I think – who for whatever reason may be going, or be about to go, off the rails. The group is active in Hackney, and for good reason. I can’t help feeling I’ve let them down.

robert.crampton@thetimes.co.uk