Tuesday 31th July, 8.24pm

Take your marks….get set….sit

And we’re off. For the next fortnight, the greatest global sporting extravaganza is being played out on home turf, as it were, and millions of us will be devoted spectators of the 14,690 Olympians who will be battling for the spoils in a myriad of disciplines. For most of us, sadly, the couch will always be more accessible than the podium.

Professor Tim Lang of London’s City University has described it as a festival of the “superfat watching the superfit” – his pithy recognition of the widespread rise in obesity among the UK’s population set in ironic contrast with the perfectly honed physiques of the world’s best sports performers.

The obesity ‘timebomb’, as it’s been called, is a complex societal problem with no straightforward solution. The trends in this country point to a rise from the current 26% of UK adults to over 40% by 2030, at an annual cost to the health service of around £1.9 billion. Yet, it’s a relatively recent problem, of no more than a few decades’ standing.

Although complex, the causes of the obesity epidemic have been well rehearsed – an increasing dependence on the car and domestic labour–saving devices, which reduces routine physical activity, our over–consumption of food which has never before been so affordable and accessible, a shift from set mealtimes to frequent ‘grazing’, the use of sugar–laden soft drinks in place of water and the predominance in the marketplace of processed foodstuffs, created by an ever more sophisticated food industry.

Many of these factors will be readily evident over the next two weeks as the diet of the couch spectator lurches towards pizza and cold beer, burger and fries (or Chariot of Fries, as The Lancet had it recently) supplemented by a bag of crisps and a choc chip cookie.

The recent furore over the commercial sponsorship of the Olympics by McDonald’s, Coca–Cola and Cadbury’s has raised important questions about the long term effects of this advertising jamboree, especially for children. Inspire a generation is one of the London 2012 straplines – but perhaps not to eat and drink junk food. The Lancet describes it as “one Olympic legacy the world can do without.”

Paradoxically, the food available at the Games’ venues is intended to create a benchmark for the future. Led by the Mayor’s London Food directive, the organisation of what has been called ‘the largest peacetime catering operation in the world’ has been meticulously planned under the Games ‘Food Vision’. With five themes covering everything from food safety to supply chains and resource efficiency, the operation to supply 14 million meals has attempted to embrace the principles of sustainable food in a comprehensive way – and to leave a legacy of transformation for the food system in London.

That will help to change the environment within which people make these everyday decisions; it can make much more widely available food that is healthy, fresh and environmentally sustainable; it can help to make people more aware of the importance of what they eat. If it succeeds, it will really help in the struggle to prevent and control obesity in this country; that could be the most important Olympic legacy of all.