Schedule your hangovers? Subscribe to a plant-based diet? Carry a Tupperware of kimchi? When what we eat bites back.

An old joke: How can you tell if someone’s a vegan? You can’t, they’ll tell you! And if not vegan in the purest sense, they’ll tell you that they’re a low-sugar, wheat-intolerant “veggan” – which is a vegan who eats eggs, because the protein is great for muscle-mass and the hens honestly don’t miss them. Or they’re on a largely “plant-based” diet with a weakness for a dirty burger on a Saturday night, but only if it comes from grass-fed organic rare-breed cattle… Because there’s already a rear-guard movement that says beef is fine as long as it’s farmed sustainably.

Yes, the Food Puritans come in many sects and many more sub-sects – but they have one characteristic in common. They are pathologically unable to stop talking (and posting) about their food choices. It is the 21st-century equivalent of writing your favourite band on your pencil case in Tippex. Paleo is the new Nirvana. Gluten-free the new Muse. And if you’re going to be obscure about it, Fodmap-free (google it) is the new Fugazi.

“It has taken over my life a bit,” says Mr James Conrad Williams, a magazine editor in London in his late thirties. “If I’m not eating food or preparing food, I’m thinking about food. And part of me can’t believe I’m saying this. I spent my twenties never going to the gym, living off booze and canapes and bingeing on carbohydrates.”

He is currently on what he admits is an “insane” regimen of six high-protein, low-fat meals each day as prescribed by his personal trainer, who believes eating little and often is the best way to reboot the metabolism, build muscle and lose fat. His diet involves a lot of turkey, salmon, egg-whites, berries and spinach, weighed out into finely controlled portions that he carries around in little Tupperwares. He has more or less given up alcohol, too – “I schedule my hangovers now” – as he can’t bear to lose the preparation time.

“I’ve always been a bit of a food snob, so I make everything from scratch. But weighing it all out takes ages – a good couple of hours on a Sunday and then at least half an hour each night. Most of the time, I’m living like a hermit going to bed at 10.30pm, getting up 6.00am. I’m lucky: I’m single, I don’t have dependents, so my time is my own – it becomes a bit of a hobby.”

Mr Williams concedes he is mainly motivated by the desire to look buff – and as most personal trainers will tell you, this is 80 per cent to do with food, 20 per cent to do with exercise. But there are good reasons for all of us to be more aware of what we’re putting into our bodies.

Obesity is now recognised by the World Health Organisation as one of the world’s gravest epidemics – globesity, they call it – with our sedentary lifestyles, processed diets and profit-driven food corporations the leading culprits. It’s estimated that four out of five products in an average supermarkets contain added sugar. That’s enough to make you fretful. The fact that the official medical advice often seems to lag behind the latest scientific evidence – which in turn appears to contradict itself from month to month – can tip it to outright paranoia. For example, the “eat low-fat” message that was standard advice in the 1980s is now often debunked by experts as a single rule to follow, as newer evidence has created a distinction between those fats that are “good” and “bad”; but still, diabetes patients are advised by doctors to eat low-fat foods, and many of the slimming industry programmes follow similar methods. This disconnect and the flurry of evidence to support niche diets or condemn specific ingredients has contributed to a huge proliferation of nutrition gurus, preaching that wheat is sinful or that kale holds the path to true enlightenment. Who can you really trust? Except of course for yourself.

Sharing a meal with one’s fellow humans ought to be a moment of coming together. In recent years, it has become a way of highlighting differences. Me? I teeter. I’d love to be able to say “I’ll eat anything” and ride above (or below) this new wave of fussiness in a man-of-the-people sort of way. But to my enormous regret, I cannot digest all dairy products properly. It means I have to say things like: “Yes, but is it buffalo mozzarella?” And: “Do you have almond milk.” Plus, I am sensitive to blood-sugar crashes, so tend to pass on cupcakes and the like, which people often weirdly interpret as a kind of tacit fat-shaming. And living with a vegetarian partner, I’ve got used to not eating so much meat. “Ooh get you, virtue-signalling!” people say.

But once you start noticing the effect that food has on your mood – once you’ve made the crucial link between physiognomy and psychology – it’s hard to stop. You start turning down your grandmother’s cake for fear of the glucose crash. You learn that you can get far more work done after a superfood salad than a super club sandwich. And then you begin to combine your health-based decisions with general-issue food snobbery – because if you’re only going to eat a few cuts of meat per week, they may as well be fancy, delicious ones.

And alongside all this, health-based fretfulness is a wider anxiety about our position in the food chain. Documentaries such as Food Inc and Cowspiracy have highlighted the horrors of factory farming, while the neuroscientist and philosopher Dr Sam Harris recently concluded that of all the things we consider normal now, industrial meat-production will seem the most barbaric to future generations.

And while “plant-based” eating is often seen as a female pursuit – associated in recent years with fragrant wellness bloggers such as Ms Gwyneth Paltrow in the US and Ms Ella Woodward (now Mills, of Deliciously Ella) in the UK – guys are increasingly taking it up for a variety of environmental and ethical reasons. Notable male vegans include the cage fighter Mr Nate Cruz and Hollywood actors Mr Liam Hemsworth, Mr Joaquin Phoenix, Mr Woody Harrelson and, it’s thought, Mr Leonardo DiCaprio (whom Ms Paltrow credits with setting her on the path to clean-eating enlightenment). Typical of the new wave are the Vegan Bros, Messrs Matt and Phil Letten, two high-fiving Seattle-based brothers who aim to create “an army of fit, sexy vegan soldiers”. They are working on a book for Penguin Random House that they hope will become the vegan bible.

“Basically, we decided to become vegan because we think it’s fucked up to abuse animals,” they tell me over email. “The meat industry has prevented us from realising that burgers and steaks are actually the food of wimps. In the past there was a stereotype associated with vegan eating. But today we have friends who are police officers, members of the military, investment bankers and pilots who are all eating vegan. Plus, let’s face it: women love a man who saves animals.”

The brothers are extremely health-driven in their veganism, and are careful to highlight the risks associated with diets lacking in protein and the over-consumption of carbohydrates and deep-fried foods. They also (perhaps surprisingly) consider veganism as an aspiration rather than an absolute: “Eating vegan is not an all-or-nothing proposition. There is a lot of middle ground. Our friend does Meatless Monday. Others eat vegan half the week. And others eat vegan except for at dinner parties and barbecues.”

And here, perhaps, is the third way. Mr Daniel Vennard is a London-based researcher for the World Resource Institute, which studies the environmental impact of the food industry. “The headline news? We all consume too much animal protein,” he says.  The meat industry is a bigger producer of carbon emissions than the entire global transport sector – with beef the worst culprit. So you can be fairly sure that your “paleo” diet isn’t doing much good to Planet Earth. As more of the world adopt American-style eating habits, consumption of animal-based products is predicted to go up by 80 per cent by 2050 and beef by 95 per cent.

Mr Vennard sees two ways out of this. One is to encourage corporations to change the types of food they promote to their customers (according to him, the catering industry accounts for around 50 per cent of all food that Americans eat). “How products are displayed and what’s made available is the number one factor that influences what people buy.” Simply offering more prominent plant-based (and low-sugar) options could have a huge impact.

And his other suggestion is to encourage individuals to reduce their consumption of meat – but not necessarily eliminate it from their diets. “Most people are going to find it hard to cut out meat entirely. But from an environmental perspective, adapting your diet to include less animal-based protein can have a similar impact to turning vegetarian. The message is reduction, not purity.”

All this suggests that a 5:2 approach to veganism might be the way forward – or, indeed whatever works for you. Eat in a conscious way in your own time, fill your fridge with as much siyez and freekeh as you like, but perhaps don’t make your gran feel bad for cooking you a Sunday roast. And there’s further encouragement. In his excellent book, The Diet Myth, British scientist and professor of genetic epidemiology Dr Timothy Spector assembles the best available data to challenge some of the claims made by the diet gurus. He came up with some unsurprising conclusions (the Atkins diet doesn’t come out looking so hot), but also some surprising ones.

We imagine that our choice of, say, Thai one night, Mexican the next, Italian the next means we eat a huge variety of food. In fact, our diets are actually much less varied than your average caveman. Apparently, hunter-gatherers would typically eat about 700 types of plants and animals each year, depending on what was in season and available. Dr Spector reports that today, our meals are overwhelmingly based on six ingredients:  sugar, salt, wheat, corn, soy and processed meats. This has terrible effects on our gut bacteria, which is increasingly linked to a range of physical and mental health problems, as well as allergies and intolerances.

Dr Spector believes we should eat specifically to replenish our gut bacteria. In practical terms, that means we should eat as wide a variety of food as possible, with special attention to fibre content and probiotics (live yoghurt, kimchi, kombucha, miso, unpasteurised cheese and so on) with occasional free-range, wild meat and fish.

It sounds like a fairly delicious way to save the world.

Do you have the radiant glow of someone who takes a mindful approach to their position within the global food chain? 

Is your dinner party conversation mainly about gym routines and the contents of your fridge? 

Do people assume you are a fussy and effete snob and look down upon their proletarian foodstuffs? 

Do you find yourself losing whole Sundays to fermenting kombucha and soaking almonds as your mates slip off to Five Guys?