Britain’s “obesity epidemic” is mainly caused by the fact that its population are lazy slobs and not because they eat too much, a shock new study called The Fat Lie has found.

The only reason the study – produced by Christopher Snowdon of the Institute of Economic Affairs (IEA) – is shocking is because it contradicts one of the great received ideas of our politically correct times: that fatties are the hapless victims of the rapacious and bullying food and drink industry which pressures them into eating and drinking far too much fat and sugar.

What Snowdon’s research clearly shows that this claim is nonsense. Yes, it is indeed true that British people are getting porkier. Since 2002 the average body weight of English adults has increased by two kilograms, contributing to Britain’s unenviable status as the fattest country in Europe.

But what is rarely mentioned by health campaigners is that this rise in obesity over three decades has coincided with a steady fall in average sugar and fat consumption.

Fat consumption has fallen from 111 grammes per day in 1974 to 81 grammes per day in 2012.

Sugar consumption has fallen by 16 percent since 1992.

Total calorie consumption has fallen from 2534 calories per person per day in 1974 to 1990 in 2012 – a decrease of 21.5 per cent.

Yet obesity has gone on rising. Why? Because, as Snowdon explains, obesity is a simple function of repeatedly eating more calories than you burn off.  And people are taking much less physical exercise than they used to. Britons are walking less (from 255 miles per year in 1976 to 179 miles in 2010) and cycling less (from 51 miles per year in 1976 to 42 miles in 2010). At work, 63 per cent never climb stairs; while 40 per cent never walk. Outside work, 63 per cent report spending less than ten minutes a day walking, while 53 per cent claim to do no sports or exercise at all.

This is worth keeping in mind next time you read some shrill lobby group – such as Action on Sugar – demanding that the government does more to rein in the food and drink industry or pushes for a ban on supersize portions in fast food outlets or higher taxes on fizzy drinks.

The reason these lobbyists get away with such drivel is because they find a ready audience among the panic junkies at places like Mumsnet and in much of the mainstream media which thrives on public health scare stories.

And the reason they find a ready audience in government is because there are few things a minister on the make enjoys more than being seen to clamp down on some greedy industry or other.

With most departmental budgets being cut, ministers can no longer make a name for themselves by spending their way into public favour. But what they can do – because notionally it’s “cost-free”, though of course it’s not really – is introduce more regulations in the name of public health and safety. It has happened to the tobacco industry. Now it is happening to the food and drink industry.

This is why reports like Christopher Snowdon’s are so unusual and refreshing. They’re one of our few remaining toeholds on reality in a world which finds it more convenient to fall for the cultural Marxist lie that nobody is responsible for their own problems and that it’s the government’s job to sort them out.