Daniel Hannan is an MEP for South-East England, and a journalist, author and broadcaster. His most recent book is What Next: How to Get the Best from Brexit.

“Let me have men about me that are fat; sleek-headed men and such as sleep o’ nights.” Most of us, on some level, share Caesar’s prejudice. Plump people strike us as cheerful, reassuring, at ease with the world. Surveys suggest that, other things being equal, we are likelier to vote for paunchy politicians, who seem solid and dependable. Think of the MPs who routinely attracted the soubriquet “heavyweight”. More often than not, they were literally heavy: Denis Healey, Willie Whitelaw, Geoffrey Howe, Ken Clarke.

Yet state doctrine remains aggressively anti-fat. Britain, we are told, is in the grip of an “obesity epidemic” – the faux-medical language portraying tubbiness as an affliction rather than a consequence of choices. The only way to turn back the contagion, supposedly, is to give more power to licensors and inspectors and regulators and clerks and censors.

First they went after sugar, demanding reductions from food manufacturers, regulating quantity and (from next April) levying a special sugar tax. But that was not enough. No government agency, after all, ever says, “Job done, let’s disband”. Instead, our body mass commissars, led by Public Health England, have moved from fizzy drinks onto crisps and burgers. “An excess of calories – not just excess sugar consumption – is the root cause of obesity,” they now say. They want what state and para-statal organisations usually want: more laws.

Have they got a point? Are we becoming porkier? And is it because we’re eating too much sugar, or eating too much in general? It’s true that there has been a rise in average weight since the 1970s as well as, until very recently, a rise in obesity. Over the past six years, according to the Health and Social Care Centre, obesity rates have levelled off in adults and fallen slightly in children. Still, they remain high by historic and international standards, at around 25 and 15 per cent respectively.

What caused the rise? Was it a sudden surfeit of unhealthy food? Come off it. If you grew up in the 1970s or 1980s, you’ll remember what kids used to eat in those days. I can recall all sorts of packaged gloop: Angel Delight, Flying Saucers, Monster Munch. OK, my childhood memories are hardly empirical data, so how about this, from the British Heart Foundation:

“Overall intake of calories, fat and saturated fat has decreased since the 1970s. This trend is accompanied by a decrease in sugar and salt intake, and an increase in fibre and fruit and vegetable intake.”

Yup, you read that correctly: we really are better at eating our greens than we used to be. Christopher Snowdon at the IEA has compiled the data, and his numbers are hard to argue with. Using official DEFRA figures, he shows that our daily calorie consumption fell from 2,534 in 1974 to 1,990 in 2012: a decline of 21.5 per cent. Over the same period, we cut our intake of sugar by 16 per cent and of saturated fat by 41 per cent.

If we have become more rotund, it must be for other reasons. And, indeed, those reasons are obvious enough. We are much less likely to walk or cycle to school. More of us now work at desks rather than in manufacturing or agriculture. Improvements in central heating and air conditioning mean that we no longer sweat so many calories off in summer or shiver them away in winter. It was reported last week that four in ten adults don’t even manage a ten-minute walk once a month.

Reported by whom? By Public Health England, the same body that is demanding action against pizzas. Our quangocrats, in other words, have the actual explanation in their hands. So why their campaign against calories and sugar – two things from which we’re turning away anyway as consumer tastes change, with no need for state compulsion?

Beyond the obvious answer that quangocrats always see government action as their first resort, there is, I am afraid, an element of snobbery. In an age that teaches us not to be censorious, anti-fattery is the one prejudice we are still allowed to indulge. It’s not exactly the fatty foods that campaigners object to; it’s the fatty people who supposedly enjoy the fatty foods. When health nannies talk of “junk food”, they don’t mean duck à l’orange or foie gras or those delicious salt caramel chocolates, darling, that we found in Normandy. They mean Doritos and KFC.

There is a long tradition on the British Left, stretching back at least to Beatrice Webb and the Fabians, of seeking to coerce better behaviour from the working classes. Although it is often dressed up in quasi-medical language, the underlying motive is as much aesthetic as sanitary.

By what right, though, do we presume to tell people what to eat? “There are,” wrote Evelyn Waugh, “no respectable reasons for wanting not to be fat”. To reject the good things in life from no higher motive than vanity was, as he saw it, a tragically modern form of decadence.

All right, Waugh was not exactly a good example of a contented fat man. Although he was the soul of elegance on the page, he was selfish, irritable and sadistic in person. So let me instead give the last word, as I gave the first, to Shakespeare, and through him to the amplest, merriest and wittiest fatty to have graced our literature, John Falstaff: “If sack and sugar be a fault, God help the wicked!”