Like Jenni Murray, who is reported to be having gastric surgery, I have recently undergone the operation to deal with my obesity. Also like Murray I am a well-educated woman who understands the basics of nutrition and the importance of exercise. I don’t know what led Murray to take the decision she did, as all circumstances are different, but I can tell you why I did it.

For one, I was in constant agony. In November last year, one month before my operation, I tried to walk from Haymarket across Trafalgar Square to a pub at the top of Whitehall to meet a friend, a distance of a few hundred metres. I had to stop twice, doubled over with crippling back pain both times. This was not even a particularly bad day.

I was humiliated on a daily basis by strangers, and sometimes by the unintended slights of well-meaning friends and loved ones. When you are this filled with pain and self-loathing, the quick fix of a plate of chips helps. A pile of Marmite sandwiches a mile high may not be love, but they can taste like satisfaction. Fried chicken feels like a comforting friend.

Of course it is self-perpetuating. Of course by eating like this you are only making it worse. But “worse” is a hard thing to understand emotionally when you’ve hit rock-bottom.

I have tried every diet going. At first I was always hugely enthusiastic and reasonably successful. On my most recent attempt I lost three stone. Then I got knocked for six in another area in my life and turned once again to calories for comfort. I was soon heavier than ever, and the cycle of self-loathing began again.

Many of those with a non-addictive relationship to food are like those drinkers who can’t understand why an alcoholic can’t stop after a couple of glasses. The constant refrain of “why don’t you eat less and exercise more”, and the pernicious notion that this is all a matter of self-control versus weakness, deny the complex emotional and psychological build up that happens with some people’s relationship to food.

For me, I knew that if I didn’t do something quite extreme, I would die soon and live the rest of my life, however long, in pain. My doctors knew that if they didn’t intervene at this point, I would cost them thousands in preventable health complications. Many thousands more than the investment in my surgery.

The surgery I had was gastric sleeve, where the surgeon cuts away about 75% of your stomach, leaving behind a sleeve or tube. Whereas most people have stomachs the size of a honeydew melon, mine would be reduced to the size of a lemon, so I would feel full very quickly. I was frightened having not spent much time in hospital before. But I was more afraid of my future without it. I made a choice that was right for me but it was not an easy choice.

Immediately after the operation I was in agony. I had to inject myself with anti-inflammatory drugs every day for a month, and I still have the bruises. Initially you are only allowed to eat liquids, so my mum made me partridge soup for Christmas dinner. Almost a year on, some foods remain hard to digest, pasta and white bread in particular. I burp a lot more often now. Luckily I have understanding colleagues.

The surgery has quite possibly saved my life, but crucially, it has also changed it. I am more active than I have ever been. I walk everywhere and am lifting weights and doing other exercises to try to tighten up the areas where I now have loose skin. Having lost eight stone I also have more social confidence. So I go out and challenge myself in new ways – ways which have little to do with my physical fitness but everything to do with my personal confidence.

Is such surgery the solution to the obesity crisis? The truth is that it can only be one part of the much wider answer to what is happening to the weight of the nation and the strain this puts on our NHS.

But like so much in the health service, we need a far greater focus on helping people before they reach crisis point. Prevention – including education on nutrition and diet but also crucially far greater emphasis on mental health and wellbeing – will be the only sustainable way to reduce the size of us and the problem.

This will take time and a huge shift in emphasis that is not going to happen overnight. Until then, it makes both moral and financial sense to give more people like me the second chance we so desperately need.