This summer, I’ve spent the parliamentary recess reading improving books, learning Mandarin and nominating my celebrity friends to do the ice-bucket challenge. No, wait – of course I haven’t. Like most people, I’ve responded to having more free time by filling it with reality television.

My particular favourite is an American import called Obese: a Year to Save My Life. In the show, Chris Powell – a personal trainer who looks like a cross between a thigh muscle and a televangelist – takes on patients who need to lose half their body weight. On the whole, over the course of a year, they do. And as I’ve watched more of the programme, I’ve become convinced that behind the blindingly white teeth and unnervingly chirpy demeanour, Chris Powell is a stone-cold genius, and possibly even the man to save the NHS.

One of the biggest lies about obesity is that it’s simply about eating too much and not doing enough exercise. It’s instructive to note how, when people talk about the subject in public, often the person faux-innocently asking, “Why not just eat a bit less, then?” is carrying a little extra padding, too. The stark fact is that most of us are fat: two-thirds of Britons are overweight or obese.

That’s because our society conspires against us and our best intentions. Outside the big cities, a car is a necessity; soon you hop into it for even the shortest trip to the shops. We sit, or stand, still for hours at work. Our bodies, which evolved to savour sugar and fat as rare and precious sources of nutrition, are overwhelmed by fizzy drinks and junk food. Even as we get more puritan about alcohol, food remains the drug it is socially acceptable to consume in public: where a previous generation might have had a drinks tray in the corner office, we have a packet of Hobnobs in the desk drawer.

The truth is that thin people don’t just eat differently from fat people. They live differently. The morbidly obese need to raze their life to rubble and build it again from scratch. On Obese: a Year to Save My Life, the subjects take three months off work to concentrate on their exercise routine. The production crew goes through their cupboards, chucking out the crisps and doughnuts and filling them with whole grains and fruit and vegetables. They get classes in cooking healthy food that tastes of something (lemon juice and chilli are usually involved). Their living rooms are filled with treadmills and free weights. In some cases, their families sign a “contract” to support them. If they reach their target weight, they are given skin removal surgery – so they aren’t dragging round six square feet of the person they used to be.

Even taking into account the inevitable behind-the-scenes manipulation that goes on – this is American reality TV, after all – the results are extraordinary. But what consistently surprises me is why the people involved in the show became obese. For some, the weight crept on after a divorce, or the death of a child, or a bout of depression. For others, being overweight is part of a general feeling of lack of control over the course of their lives. One episode followed Jacqui McCoy, who went from 25 to 11 stone and who started overeating when she was raped at the age of 14. As part of the year-long transformation, many of those trying to lose weight speak to a therapist, and that must be one reason for the programme’s success.

“Obesity is a symptom,” is how Emma Burnell puts it. The Labour blogger had a gastric sleeve operation this year and has since lost eight stone. “Everyone who is overweight has a different reason.” She believes any policy response to Britain’s ballooning weight has to address the psychological as well as physical aspects of obesity. “It would have to bring in mental health, because, in my own experience, I knew all the good rules about food and exercise – but there was something stopping me.”

And this is where I think Obese: a Year to Save My Life has a lesson for the NHS. We already know that obesity costs the health service more than £5bn a year, both through increased rates of heart disease and other illnesses, and through the costs involved in adapting medical equipment for bariatric patients. Yet the kind of holistic, intensive intervention offered by Powell just isn’t available – our counselling services are overstretched, and the NHS deals far better with emergencies and acute cases than it does with chronic, complex problems and the need for preventative medicine.

Admittedly, gastric sleeves and bypass operations are available – though there is not enough capacity, as Burnell found out when her operation was outsourced by King’s College trust to a private hospital in Chelsfield. (In Wales, the health service plans to increase its bariatric surgery capacity from 80 to 300 a year by 2018 to cope with demand.) As for skin removal, it is defined as cosmetic surgery and is rarely funded by the health service. That means patients are given a second chance but saddled with excess skin that chafes, and gets inflamed, and perhaps infected. It’s certainly a disincentive to do exercise.

There’s an echo here of “Million-Dollar Murray”, Malcolm Gladwell’s celebrated essay for the New Yorker – in which he calculates that over a decade, a single homeless man called Murray Barr cost the state of Nevada a million dollars as he bounced around police stations and hospital emergency departments. “It would probably have been cheaper to give him a full-time nurse and his own apartment,” Gladwell concludes.

The same is true of the morbidly obese. It would cost the health service many millions to offer them intensive support – cognitive behavioural therapy, diet education, free exercise equipment, plus gastric surgery and skin removal where appropriate. But in the long run, it will cost more not to offer people a second chance.