The London Eye, a landmark since the Millennium, welcomed the first day of a new sponsor yesterday. Coca-Cola plans to play “an even greater part in future moments of happiness and celebration in the capital”, according to Jon Woods, general manager of Coca-Cola UK and Ireland. It’s ironic that the arrival of the red and white trademark colours of a global drink renowned, in its original form, for providing a shocking nine spoonfuls of sugar per 330ml can, comes at the end of a week in which, as in every week, 500 children received hospital treatment for dental decay, and there have been a stream of warnings about the health of the nation. We are swallowing far more sugar, salt and fat than is good for us – or the public purse.

One warning came last Thursday when On Rock or Sand: Firm Foundations for Britain’s Future was published, edited by John Sentamu, archbishop of York. It tackles a range of issues spawned by a low-wage economy and refers to the current epidemic of obesity that, for the first time in many decades, means that some children may live shorter lives than their parents. On Rock or Sand rightly points out that “choice” in diet is complex. It is influenced by income, class, culture and societal pressure among myriad other drivers, not least the seductive practices of the marketplace in disguising what goes into processed food and employing the hard sell in honeyed words that are particularly effective on children.

Low-cost food and medical progress have ensured longer lives but decades with a long-term condition can also bring misery. The book quotes Department of Health figures that show 62% of adults and 28% of children are overweight or obese. The health problems this spawns include type 2 diabetes, cancer and heart disease, between them costing NHS England more than £5bn a year.

Last Wednesday, Andy Burnham, Labour shadow health secretary, launched Labour’s public health strategy. It served up even scarier statistics. Unless the rise in obesity is reversed, the cost to the NHS of diabetes alone will rise from £10bn a year to an unsustainable £17bn a year by 2035. While the World Health Organisation recommends that 5% of our food energy should come from sugar, children are consuming triple that amount. Further bad news came from the Youth Sport Trust, in its Unlocking Potential report. Only 21% of boys and 16% of girls are exercising sufficiently. Physical education lessons have slumped below the miserly two hours a week set by the previous Labour government. The trust is rightly calling for five hours of physical activity a week in state schools to match that offered by private schools. Eating too much and doing too little may be a personal “choice” for some, but it’s one the nation can ill-afford. So what’s to be done?

The first is to show common sense. It is incredible that Merlin Entertainments should consider Coca-Cola a suitable sponsor for the London Eye. As this paper reports, John Middleton, vice-president of the UK Faculty of Public Health, says: “Coca-Cola is the flagship for sugar marketing and therefore the flagship for rotten teeth and diabetes.” The second imperative is for government to wake up to the scale of the health disaster on its doorstep. In February 2010, David Cameron laid out his vision for “a new age of government”. “If you combine this very simple, very conservative thought – go with the grain of human nature – with all the advances in behavioural economics,” he said, “I think we can achieve a real increase in wellbeing… without necessarily having to spend a lot of money.” Money has certainly been tight even as public health issues, supporting improved wellbeing, have disastrously dropped off the agenda, issues such as plain packages for cigarettes, minimum pricing on alcohol and an end to selling sports fields. In 2013-14, the NHS budget was over £95bn, compared with only £1.8 bn allocated to Public Health England to promote “wellness”.

The lack of investment in prevention, married to politicians’ fear of the charge of “uber-interference” and “the nanny state”, means that multinationals have too little restraint. We accept the so-called nanny state edicts on seat belts, smoking and drink, so why can’t the state take a much greater role in improving the food that is sold to us and marketed to our children?

Andy Burnham calls this “finger wagging”. On the contrary, it is lifesaving. It is welcome that Burnham has promised that Labour will legislate to reduce the sugar, fat and salt in foods sold to children. Such steps require rigour in the face of food industry claims that it’s difficult to differentiate between “family foods”. The “responsibility deal” in which businesses voluntarily take action to improve public health hasn’t produced many results. Last week, for instance, Asda promised to reduce 22% of added sugar in some 26 of its own brand drinks, amounting to a reduction of a staggering 3.25bn calories. However, Professor Graham MacGregor of Action on Sugar says that only reveals the scale of what remains to be done. Little bits of action are no substitute for sugar reduction mandated by government policy. As Burnham correctly said last week: “For change to work in a market context, all players need to be following the same rules.”

Dame Sally Davies, the chief medical officer, has warned that a 20% tax on sugar in fizzy drinks may be required. It makes sense. Advertising to children is another issue requiring intervention. Promoting unhealthy products is restricted on children’s television but it is unfettered online in “advergames” and between 8pm and 9pm on television when, according to Malcolm Clark of the lobbying group, the Children’s Food Campaign (CFC), ads are a junk food paradise. Burnham intends to ask the committee on advertising practice and the Advertising Standards Authority how children can be better protected. That is a cop-out. The CFC, backed by the British Heart Foundation, has rightly proposed a body independent from the advertising industry to monitor and regulate marketing to children and tougher enforcements.

Managing diet, taking exercise and aiming for fitness can’t be directly stipulated in law. Parents, government, the community and the commercial sector all play a part in taking responsibility. However, the balance of power is skewed against the ordinary citizen, particularly those penalised by profound health inequalities, and towards those with profit in mind. The state has to play a far more dynamic role than Labour envisages or the coalition provides, to ensure that what does us good, at a price we can afford, becomes the established framework for a healthy life.