It may come as a surprise, but many of the major UK fast food chains have restaurants across the NHS in England. What isn’t surprising is that the head of the health service now wants this to stop.

NHS England’s chief executive Simon Stevens announced at the NHS Innovation Expo conference in Manchester this week that he wants to curb sales of fatty, salty, sugary food by fast food chains in hospitals.

He is also seeking to ensure that new contracts in hospitals also give customers a healthy option, calling for fruit and savoury snacks to be dispensed in vending machines and for chocolate and crisps to make up only a fifth of the food available.

There will be no outright ban, but he warns the writing is on the wall for fast food and vending firms that do not change their menus to offer healthier alternatives – although the timeframe is not clear at this stage.

This will affect a number of fast food chains, including McDonald’s, Burger King, Pizza Hut, Greggs the bakers and Subway, which all have restaurants in hospitals across the country.

It seems difficult to argue against, but with this decision Stevens risks opening a major can of worms.

Coffee shops such as Costa and traditional CTNs such as WH Smith do not fall under the remit of this health drive, but a number of products from these suppliers contain equally (and occasionally higher) levels of sugar, salt and fats as those offered by the fast food chains.

There are reports that there are far more Costas and WH Smiths in hospitals across England than fast food chains.

This raises the question as to where junk food ends and healthy food begins – and just how such a policy will be implemented and policed.

Since his appointment two years ago, Stevens has made it his mission to tackle public health issues, with his crosshairs particularly set on tackling the obesity epidemic.

Ultimately, patients are free to choose their meals and have the option of eating food provided from hospital kitchens (although low food budgets make these the butt of many jokes).

These restaurants are also open to those visiting patients and to staff. A speedy food service is needed in hospitals – by definition, no-one can do this better than fast food companies.

But there remains the uncomfortable truth that foods which are high in fat, salt and sugar are being sold within state-funded hospitals that have unbridled access to a captive audience, making free choice difficult. Obesity levels among NHS staff are also a factor in this decision.

Fast food chains are not the only culprits: if they are to be phased out, then the same should apply across all suppliers. Otherwise, Stevens risks demonising one food supplier over another – but not ultimately tackling the obesity problem.