Sorry Santa, but there’s no sugar-coating this: you’re eating too much. And it’s nobody’s fault but your own. Human beings have agency. You have it within your power to cut down.

An excellent book written by restaurateur and policy adviser Henry Dimbleby, with his wife Jemima Lewis, sets out the figures. They’re shocking. In Ravenous: How to Get Ourselves and Our Planet into Shape, Dimbleby shows that in some 70 years we’ve regressed from being a nation where almost nobody was obese and less than 4 per cent of people were overweight, to today’s Britain, where some two-thirds are either overweight or obese. The UK is shamefully high on the list of fatties, but the rest of the West faces similar problems.

The consequences are dire. The cost to the nation as regards the NHS, social care and the economy is about £100 billion per annum, and rising fast. Eating has overtaken smoking in the damage it’s doing to us. So, gritting my teeth, I accept Dimbleby’s recommendations that government use the tax system to discourage the manufacture and consumption of the things that, consumed in excess, are killing us, like sugar, salt and fat; take at least some responsibility for helping feed the poorest children; regulate marketing techniques that encourage over-purchasing (like ‘buy one, get one free’); and – where definitions are easy, which they often aren’t – restrict the advertising of junk food.

My observation of seriously overweight friends is that they just won’t stop eating

Many readers will react instinctively against this nanny-state approach, but Dimbleby has persuaded me. After all, he’s not trying to ban foods, just nudging our habits by upping price and restraining marketing. I hate to say it, but he’s resoundingly right.

I have, though, one problem with this important book. I’ll stick my neck out here. Yes, these government measures would help; yes we should try them; but no, they’re unlikely to affect the public’s eating habits at more than the margins. Most of us will still be able to afford to get fat.

Yet not everyone will. So why’s that? Food is lovely. What really restrains gluttony? The reason stares us in the face – but we seem coy about admitting it. ‘Mirror, mirror, on the wall…’

We don’t want to look unattractive. We know that our weight is determined by how much we eat. And almost everybody knows that however hard it may be to say no, it is within the power of most people to refuse a second helping, decline pudding, resist the chocolate at the checkout, skip the occasional meal and walk rather than drive when the journey isn’t that far. The incentive? Health will be one concern: we do want to keep fit. But face it, my friends, we think it unattractive to be overweight. We are sometimes secretly censorious of those who are. We’d hate to think others were politely ignoring mentioning our weight problem to us.

When we watch films we may warm to the cuddly people but it’s the svelte (or proportionately curvy) ones who set the pulse racing. We don’t count a double chin as a facial adornment. These criteria are woven deep in the fabric of the way we look at each other and, more importantly, at ourselves. If you doubt their power to influence behaviour, or doubt we think it possible to exercise some control over our own feeding habits, look at the trillions of words published on weight-loss diets.

The most powerful tool in the hands of those who, for reasons of health, wish to encourage people to eat less is to play on their willingness to do so for reasons of beauty. This is the motivation we all acknowledge but are becoming fearful of blurting out: we care how we look. Fat is unattractive. I dislike the phrase ‘fat-shaming’ but it touches on something that must be central to resisting the advance of obesity. ‘Which of you by taking thought can add one cubit unto his stature?’ (Matthew 6:27). But which of us, by taking thought, cannot shed a pound or three?

The fault, dear Brutus, is not in our stars but in ourselves. Treat with suspicion science that struggles to define its terms while offering a simple, aha! explanation of our ills. Every journalist knows that telling our readers their difficulty is somebody else’s fault is music to their ears. ‘Thank heavens,’ they think, reading Dimbleby on ultra-processed food (UPF), ‘it’s not that I’m weak-willed. I’m a victim: the victim of unscrupulous multinational food corporations. The government must act.’

Undoubtedly big food companies have their eye first on profit. Undoubtedly some foods are more processed than others, and some of these are calorie-rich yet fail to fill you up, so you want more. Undoubtedly those who sell food take advantage of this: we eat more crisps than baked potatoes. But my observation of seriously overweight friends or obese people on trains is that they just won’t stop eating – eating anything really, ultra-processed or not. And there’s something fishy about this rather sudden unveiling of UPF as the author of their misfortune.

‘The British,’ writes Dimbleby, ‘eat more UPF than any other European country’ – in fact 57 per cent of our diet. This compares with 46 per cent for Germany, 15 per cent for France and 14 per cent for Italy. So are we four times fatter than the Italians? I looked at the tables. Across Europe there are very sharp differences in UPF consumption but none at all in rates of overweightness and obesity. We’re not much fatter than the Italians. Odd.

The oddity led me to a survey published in 2021 in the European Journal of Nutrition on ultra-processed food consumption in adults across Europe. The authors conclude that this consumption ‘was not observed to be associated with country-level burden of high [body-mass index] despite being related to a higher total sugar intake’. Crikey! It’s worth reading that again. I did. Then I looked at several related scientific publications. I found footnote references to the EJN survey but no attempted refutation. I sensed that contributors, who did offer evidence of other harm from UPFs, are ducking the obesity question.

Let’s carry out a test on two Santas. Between now and Christmas we give one of them access to limitless quantities of shop-bought mince pies, full of ultra-processed ingredients. The other Santa has unlimited access to homemade mince pies, like grandma used to make. At Christmas we’ll measure their respective weight gains. If the first is significantly fatter than the second, I’ll eat my (high-fibre) hat.