My attempt to buy a swimsuit a month ago was the last straw. I’d joined a health club with the right kind of swimming pool for fitness swimming — long lanes and ladies only at certain times of the day.

I was determined to begin a programme of regular exercise to lose weight and get my joints moving.

I couldn’t possibly wear the tatty old cossie I’ve had for years. I tried on what I thought would be my size (and, no, I’m not prepared to reveal it). I couldn’t get it past my thighs. I went up a size. That got stuck on the hips.

At 64 Jenni Murray has admitted she is obese

Eventually, I did get one to fit — I could have pitched it as a tent and housed a family in it — and I couldn’t believe how hideous I looked.

I reminded myself of the women I would have sniggered at in my youth, muttering: ‘How could she have let herself go like that?’ How indeed? But it had happened. To me.

I braved the humiliation of the changing room and managed ten lengths in the pool. I even booked yoga and Pilates classes.

But back in the changing room, as I struggled out of the soggy swathes of fabric and stared balefully at my body in the mirror, it was blindingly obvious the problem had gone beyond a few exercise classes and passing on the pudding. Way beyond.

Most worrying was what the bulging stomach told me about the risk to my health. My shape screamed out ‘heart attack’, ‘type 2 diabetes’ and possibly even ‘cancer’ (and I certainly don’t want another brush with that, eight years after I was told I had breast cancer, from which, thankfully, I am in remission).

These illnesses are all, as we know only too well, influenced by obesity. And there was no question about the terminology any more. At 64, I’m far too old to pass myself off as chubby or plump. Even fat doesn’t cover it these days. Obese is the only word for it.

Something radical has to be done. And reluctantly, I am coming to the conclusion that ‘something’ is a gastric band.

For those who aren’t aware, a gastric band is an operation in which a band is stretched around the upper part of your stomach, creating a small pouch to hold food. Because your new ‘mini’ stomach is so much smaller, it limits the amount of food you can eat by making you feel fuller more quickly.

It’s the gentler, less drastic cousin of the gastric bypass, in which a tube is created to divert food directly from the upper stomach to the small intestine, which reduces not only the amount of food you can eat, but also the amount absorbed. It’s permanent, while a band can be tightened or loosened.

The number of gastric bypasses on the NHS has risen six-fold in the past five years, according to official figures, while gastric band operations have doubled. The estimated cost is £85 million a year. Many more will have been carried out privately.

Jenni Murray, aged 21, pictured looking very slim on her wedding day with her first husband Brian

I know some people will criticise me for joining this stampede and opting for a quick fix to my obesity. But I’ve spent so many years dieting and exercising with no long-term benefit I feel I’ve run out of options.

‘Eat less and get some exercise, you lazy lump,’ the more cruel detractors will cry, to which I reply: ‘Oh, I have done, believe me.’

My dieting history is legendary. I’ve tried them all — cabbage soup, Atkins, Dukan, 5:2 — and have lost stones and stones. The most was seven stone in 2008, which I lost through sheer effort and willpower.

But then, goal achieved, each time I have started to relax and eat normally, believing I could maintain my new, healthy weight simply by willing the scales to stay put. Yet every time I’ve watched, despairing, as the numbers soared up once again.

With her son Ed, aged 1. She says she will always take food offered to her by her children.

There will be those who will see my determination to join the skinny ranks as a form of betrayal. Like Fern Britton before me, they see us jolly, chubby types forging careers and holding together successful marriages as living proof that weight is no barrier to happiness.

I admit I, too, have been disapproving in the past of people depending on the surgeon’s scalpel to fix a physical inadequacy and I certainly wouldn’t approve of scant NHS resources being spent on breast enlargement or making a perfectly adequate nose into a cuter, turned-up one.

But this is not about vanity — though being able to get into a size 12 swimsuit again would be a bonus. No, this is about my conviction that my weight problem isn’t my fault and a gastric band could save my life.

A cop-out? A lazy, fat person explaining away her lack of will-power on ‘big bones’ or ‘slow metabolism’? I promise you that is not the case.

There’s a theory that a body senses it’s been in starvation mode and will do its best to lay down fat for the future as soon as it gets a chance. Hence the yo-yoing so many dieters — myself included — experience when they find they put on more weight after a diet than they had started out with.

In the past, I’ve always been reluctant to blame my burgeoning waistline on anything other than my tendency to live my life from one plateful of something lovely to another. Work hard, then reward yourself with a tasty titbit.

Kate Moss had it so wrong when she famously said: ‘Nothing tastes as good as skinny feels.’ No, Kate, for me, nothing tastes as good as food. Hot crumpets dripping in butter. Freshly baked scones with whipped cream and jam.

Jenni in 1994, at the beginning of her broadcasting career, presenting Woman's Hour on Radio 4

Food is one of life’s great pleasures. I am constantly surrounded by temptation. What do I say when a chef bakes a perfect Black Forest gateau on Woman’s Hour? ‘Sorry, I don’t eat cake.’ Don’t be silly!

So is it any wonder, when I’m feeling down because my clothes don’t fit or I’m finding it tough to make it up the stairs, that I’ll cheer myself up with something delicious?

‘Chips, Mum?’ ‘Why not?’ ‘How about a pudding?’ ‘I really shouldn’t, but . . . OK, go on.’

So, it was with a mixture of despair and joy that I read recent research from Aberdeen University on the ‘lazy brain’. The theory goes that, as we grow older, the cells that control appetite become less efficient, leading to a mistaken assessment of how much food our bodies need.

Some will see my determination to join the skinny ranks as a betrayal. Jenni Murray

As we age, we need less food because we tend to move around less, but our brains fool us into thinking we need to eat more to feel full — hence middle-age spread and the tendency to gain two stone by the age of 50 and then an average pound or so a year after that.

It was as I turned 50 that I began to resemble a blown-up balloon. Hungrily, I began to research the science supporting this theory.

The pituitary gland in our brain produces the hormone pro- opiomelanocortin peptide (POMC), which is responsible for monitoring our appetite and consequently our body weight. As we age, the production of this hormone slows down, causing the brain to stop signalling efficiently when you have had enough to eat.

As these signals slow down, we over-eat and so put on weight.

Aged 40, at Northcote Road market in Clapham. Jenni says she is constantly surrounded by temptation.

Professor Laura Heisler, who led the research, is working on a diet pill to kick-start the process of sending these important signals again. Meanwhile, she advises eating a bit less than you think you want and eating slowly to give your lazy brain cells time to act.

This research chimed with a conversation I’d had with Dr Billy White, a consultant paediatrician who specialises in obesity and diabetes in children, which is what we’d been discussing on Woman’s Hour.

It was after the programme that the subject of weight gain in the older population came up and it was clear that I had a personal interest in the matter.

‘Bariatric surgery — the term that covers all types of weight-loss surgery — is the only answer in older people where the weight problem is difficult to shift and it’s potentially having a serious effect on other aspects of health,’ he said.

And this was pretty much what my GP had said to me recently as he expressed concerns about my reduced mobility thanks to the sciatica I’ve written about here (I’ve had the steroid jabs, by the way — much better, thanks for asking) and the unnecessary pressure on my metal hips.

But Dr White said something the GP hadn’t mentioned. ‘The reason bariatric surgery works so well is not just because it reduces the amount of food your restricted stomach can consume, it also has an effect on the hormone system that controls appetite and body weight.’

There are lots of scientific papers that suggest gut hormones may play a significant role in weight loss following bariatric surgery.

The research clearly points to the fact that while dieting causes an increase in ghrelin, known as the ‘hunger hormone’, surgery actually causes a decrease.

Despite an illustrious career as a journalist and broadcaster, Jenni has always been conscious of her weight

My inadequacy in the scientific comprehension department means I don’t quite grasp how it works, but I’m beginning to be convinced.

These changes cause corresponding alterations in the brain cells that make the POMC peptides that are primarily responsible for appetite and body weight.

Could it be that surgery gets those lazy cells working again?

I’ve arranged to see Dr White in a few weeks to discuss these findings in more detail and weigh up the benefits and potential risks of going ahead with the surgery.

Earlier this year, the National Institute of Health and Care Excellence (NICE) agreed to extend their guidelines on who should be offered the surgery on the NHS.

In the past, it was available only to those with a body mass index (BMI) of more than 40, who were considered ‘morbidly obese’.

Aged 34, with two month old son Charles

They propose making it available to those with a BMI of 30 to 35, who have been diagnosed with type 2 diabetes. This could mean 800,000 people would be eligible, but the costs of the surgery, it’s argued, would be more than balanced by the savings made by eliminating some of the terrible consequences of diabetes, including blindness and the amputation of limbs caused by damage to the cardiovascular system.

So, I’m really not considering such a radical move out of mere concern for the way I look. It’s because I don’t want cancer, diabetes, a stroke or a heart attack to fell me quite yet.

I don’t want to die, and I have no desire to become a burden on my children or the NHS. I don’t yet have diabetes. To be honest I don’t know my BMI, but I have my suspicions that I am among the one in four people in the UK who are clinically obese.

Half of all of us in Britain are overweight and we will cause a terrible strain on the NHS if we carry on this way.

I took out private health insurance nearly 20 years ago on a ‘just in case’ basis and if the doctor agrees I’m suitable for surgery, I’ll ask them to pay for it.

However, if they refuse, I’ll have no hesitation about going ahead on the NHS — I’m pretty sure I’m big enough to meet the criteria — and I am convinced it will save public money in the long run if my health risks are reduced.

I have to say I feel nervous about having the procedure. In the meantime, I am trying to eat a bit less and am sticking with the swimming, yoga and Pilates.

If it happens it will be an end to lovely dinners with friends, chips, puddings and those occasional glasses of rich, warm red wine — nothing but calories in that.

Will life be worth living with its primary pleasures gone? Those I’ve enjoyed for so long?