Debt means cuts. There is no way around this obvious fact of life. If you have run up serious debt on jam yesterday, there will be no jam today nor any jam tomorrow, for many tomorrows to come. You will have to spend more of your income on debt and less (if any at all) on jam. Vast public debt such as ours means huge public-services cuts.

Yet most politicians seem either unwilling or unable to talk about it like responsible adults. There will, for instance, have to be cuts in the National Health Service, no matter what they pretend. Last week the NHS Confederation predicted an enormous shortfall in NHS funding starting in 2011 – the equivalent of a cut of £8-£10 billion. The government is trying to get out of admitting this, but failing. The Tories have admitted something of the sort but are backtracking. All that’s clear is that the golden years of NHS spending are over.

Yet at a timely conference about the NHS run by the think tank Reform, Mike O’Brien, the health minister, made an asinine remark: “The future of the NHS has never been brighter.” Perhaps one should not blame him: he was standing in at short notice for Ben Bradshaw, who had just been shuffled – in itself something that’s wrong with the NHS: new people constantly stepping in at the last moment and in a hurry.

Since Labour came to power there have been no fewer than five health secretaries, all serving only two years or less (apart from Alan Milburn, who served about four), and now we suddenly have a sixth. It is daft. The NHS is the fourth-largest organisation in the world, after the Russian army, Indian railways and Wal-Mart. The idea that anyone at the top can begin in two years to understand what should and shouldn’t be done, let alone do something, is madness.

For secretaries of state to skip at speed from post to post, using each ministry as a stepping stone in their career or as a way to prop up a self-serving prime minister, is not government; it is musical chairs.

Under Labour, spending on the NHS has nearly tripled while productivity actually fell by 4.3% between 1998 and 2007. Last week the Office for National Statistics issued a truly frightening report outlining the failure in productivity across the public services, despite huge spending increases. From 1998 to 2007, public-sector spending went up by 75% while productivity fell by 3.2%.

At the Reform conference, well-qualified people proposed all kinds of ways in which the NHS could achieve more for less, many of which we’d heard before.

The most important were cultural – shifting mindsets, decentralising money, responsibility and information, empowering the patient, persuading people to abandon layers of bureaucracy, stopping national pay bargaining, renegotiating daft contracts with GPs and consultants that pay them more to do less, removing perverse incentives and introducing good ones and so on.

Admirable though much of this was, many people were pessimistic: cultural change inevitably takes time. I think what’s needed now is a quick fix or two – something simple and fast-working, something even a health secretary with attention deficit disorder can understand.

The most obvious, I realise, has to do with preventing chronic illness in the first place. Until last week I had always thought this fell into the category of bossy government intrusion – wasting squillions on telling people how many potatoes to eat and on useless quangos. To me the phrase “public health” had come to mean “public nuisance”.

However, my mind was changed by Christine Hancock, a former senior nurse and NHS manager and now European director of the Oxford Health Alliance, an international public health charity. She began by saying – and who can disagree – that she was exhausted by NHS reform. The service is obsessed by structures and finance, to the detriment of primary care. Yet the main burden upon the NHS comes from chronic diseases – cardiovascular disease, lung disease, diabetes and cancers – which, apart from causing drawn-out suffering and death, are hugely expensive to treat. All these conditions are often caused or made worse by smoking, inactivity and a bad diet.

Everyone knows that, but few people seem to care. The acute hospital ward where I spent three weeks as a visitor recently was full of people almost too big for their beds, and certainly too heavy to lift, regularly visited by their outsize relations: people of normal weight were in a minority, except among the nurses and doctors. Our streets and shops are full of people who are not just fat but obese, waddling from groaning sweetie counter to busy burger bar, eating food that is in effect poison. Sugar is full of calories that make you fat and sick and it’s addictive.

And it can give children serious mood swings. Most fizzy drinks are bottled disease. There are about 550 calories in a Big Mac, which by itself is well over a quarter of a woman’s or a child’s daily energy needs. Yummy thingies and treatlets and biccies are swimming in invisible fat to fuzz up your arteries. To give such things to children is nothing short of child abuse. As for good food, according to Hancock, only 25% of the population eat five portions of fruit or vegetables a day, and 50% of children – an astonishing figure – eat no fruit or veg at all in the week.

I am sick of people talking about health education and “lifestyle choices”. What’s clearly needed, contrary to everything I’ve always thought, is a little compulsion. Our NHS and our economy cannot take the consequences of poor lifestyle choices. First, all schools should make healthy meals compulsory and should offer pupils one meal only – no choice – and make them eat it. (Allowances would be made for religious taboos and ill health.)

Second, the polluter must pay, as the Greens always say. The polluters who manufacture junk food of all kinds should be forced to label it, like cigarette packets, with simple information about calories. And the food itself, the pollutant, should be made extremely expensive, by high taxes, so that those who are polluting their own bodies would have a powerful incentive to stop.

Admittedly this is hard on the poorest, who eat the most junk food, but bad diets are not only bad for them. They are also expensive for the NHS and us. Healthier diets will not provide a quick fix, but the taxes from junk food could go straight to the coffers of the local NHS organisations, and that would do something fast to ease the pain of the inevitable cuts to come.

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