Recently, while it was being extended into an intergalactic megastore, my local supermarket closed for a whole week. This major event happened to coincide with a malfunction in my fridge. The perfect opportunity, I thought, to shop as green campaigners beseech us. I’d pop into the local butcher, fishmonger, deli and greengrocer, make foody badinage, inquire what was in season, sniff tomatoes, squeeze melons. Since nothing would keep in my lousy icebox, I had to do this every day, just like a frugal Fifties housewife or an Italian mamma.

I preen myself as being a virtuous cook-from-scratch paragon (except for pastry and custard) but after seven days of popping and chatting, sniffing and squeezing, I was exhausted, bored and had achieved very little else. The morning our store reopened – and the fridgeman cometh – I was down those aisles like a deranged pensioner in Supermarket Sweep. Modern life may be rubbish, but it is magnificently convenient. And to pull away from the force field of its comfort and ease, takes a stronger will than my own.

This week modern life claimed two far more significant victories. Despite £220 million in government investment, 30 per cent fewer children are eating school meals now that Jamie Oliver has insisted they are healthy. Another £119 million government scheme to give a daily piece of fruit to every child aged between 4 and 6 does not, it seems, establish an enduring apple habit.

And because the free carrot isn’t working, there have been calls for the stick: Oxford University’s Department of Public Health has suggested a tax on junk food. But will, say, £1 on a ready-meal make people cook fresh food? Would doubling the price of doughnuts make us prefer grapes? Or would it just ratchet up the financial stress for the (probably low-income) bearer of the shopping basket? There is not a child in state school who is not fluent in nutrition. I have sat through at least three class assemblies on healthy eating, often being lectured on the evils of fat and sugar by small children with straining waistbands.

Britain’s children are not fat for lack of scaremonger food-labelling, education or government initiatives. They are fat, because we are fat. We are fat, because modern life makes us fat. And while we beat ourselves up about our rancid British snack-and-go eating habits, our lack of Mediterranean menus, we should remember that a third of children in Italy and a quarter in Spain are overweight. And, counter to its culinary arrogance, France is set to have the same proportion of enormous enfants as – horreur! – America by 2020. French mothers are serving more ready meals and le dîner, which once stretched over several dainty courses and 88 minutes, is now consumed in just 38, often in front of the telly.

Moreover, according to the World Health Organisation, child obesity is now common in Mexico, Peru, Thailand, Morocco and industrialised China. Most bizarrely, in parts of Africa three times as many children are obese as suffer from malnutrition.

Wherever people move to cities, they earn a little more money and do not need always to toil over stoves. They can buy fast-food from stalls, which is less effort, and, anyway, children – programmed to gorge on fats – prefer it. They can’t afford many treats for their kids, but an ice-cream or a cola brings a smile, so why not one every day? Eventually they can afford labour-saving devices, microwaves, Hoovers. Their lives are less wearying and drudge-ridden. Sanitation means they don’t need to fetch water; public transportation ensures they no longer walk many miles to work. Modern life, progress, mean effort declines, yet our appetites remain undiminished.

Then culture reaches our present rung of development, where in order to be thin it is necessary to run counter to every prevailing social force. Few of us do manual work, so we must contrive to replicate hod-carrying or steeplejacking in a gym. I puff around the park not to get slim but to avoid getting any bigger, otherwise at my desk I wouldn’t burn enough calories to ever enjoy pudding. Exercise is rarely integral to our daily lives; we have to insert it artificially, to “make time” for a workout. No wonder it feels such a fag.

We do drive short distances, rather than walk, not because we are lazy but because we can afford the petrol, so why would we not? To be slim in the modern world requires 24-hour discipline, a constant denial of the most convenient, delicious, alluring, instantly satisfying option. Moreover, even if we manage to maintain our own iron will, how do we police our children? How do we instill the unfashionable virtue of self-denial? It is irksome always to say “no”, when your instinct is to delight those you love. Grandparents would once slip kids a bag of chocolate buttons: now their indulgence runs to a tree-trunk Toblerone.

These days even middle-class children are pretty fat. In our age of plenty, the fridge is forever full. Fat kids are an embarrassment: they make their parents look weak, irresponsible and chavvy. We envy those whose progeny are picky eaters. Yet it is not the done thing to tell a six-year-old “no, you can’t have pizza, because you’re getting man boobs”. In particular, parents of girls oscillate between horror at the obscene bulge beneath the crop top, to terror that a misjudged word might incubate anorexia: both outcomes of affluence.

I am always asking my sons, before they slip another slice of bread in the toaster: “Are you really hungry?” – because they can’t be, but then how would they ever know? Of course, kids will sneak out of school, away from Oliver’s broccoli bakes, while they have cash for KFC. Children won’t demand apples from parents when the free school fruit has ended if they’re offered Jaffa Cakes. Kids don’t think about coronary bypasses and type 2 diabetes. They live in the moment, in the mouthful.

Obesity is reaching such proportions that public health is surely coming to a crossroads. Persuasion and education are ineffectual. We either have to become totalitarian. Ban the sale of certain foods outright, perhaps fizzy drinks, whose empty, chemical calories make children fat without even making them feel full. Make school meals free, healthy and compulsory until 18, dole out free fruit to all primary children, start every school day with Soviet-style mass exercise.

If not, then we need to reflect that history is full of worse fates than ordering up a bigger size of trouser, then eating ourselves to death.

Times Recommends

• Fundamentalist brew: faith and power
• Big guns wheeled out for the marginals
• Wanted: new merchants of light