What We Eat

Why this article exists

Today, in much of the world, the average person gets more than half their daily calories from ultra-processed food — substances their great-grandparents would not recognise as food at all. They eat alone, in a hurry, at a screen. They don’t know which foods are in season. The wisdom they have access to is whichever influencer their algorithm fed them this morning.

This piece tries to put three things in one room: the real, current science of how food shapes the body and mind; the wisdom traditions — Ayurvedic, Mediterranean, East Asian, Indigenous — that have known a great deal of this for millennia; and an honest safety net about where “food as medicine” tips into harm.

The story most of us live

Imagine a kitchen, four generations ago. A grandmother is shelling peas at a table. Something is fermenting in a clay pot in the corner. There’s bread cooling somewhere. The meal will involve everyone who’s home. Before anyone eats, somebody says something — a prayer, a thanks, a moment of quiet. The food is from within a day’s walk. Nobody has heard the word macronutrient.

Now picture this morning. You ate something engineered in a factory, in seven minutes, half-watching a screen. You don’t remember it now. By 11am you were hungry again and didn’t quite know why. By 3pm your mood was low and your energy was low, and you assumed both were about your life, your sleep, your work — not the coloured cereal you ate at 7am that contained sixteen ingredients and four colours that don’t exist in nature.

The deeper story this article wants to tell is that almost every dietary “trend” of the last twenty years — Mediterranean, anti-inflammatory, gut-healing, plant-forward, fermented, time-restricted, mindful — is in some real sense a recovery of what the first kitchen already knew. Once you see that, the food conversation becomes simpler. Not easier — but simpler.

Modern science is, slowly and rigorously, rediscovering what your great-grandmother could have told you in five minutes.

— the quiet thesis of this piece

What food actually is

For everyone

Food is four things at once. Modern nutrition science talks fluently about the first, is starting to take the second seriously, and almost never mentions the last two — which is part of why its advice feels hollow even when it’s technically right.

• fuelThe calories and macronutrients that keep your engine running. This is the layer nutrition labels and clinics talk about — and almost the only one.
• informationEvery bite signals your hormones, immune system, gut microbes, sleep, mood, and genes. Food is biological text your body is constantly reading.
• communityFor most of human history, the meal was the social unit. Eating alone is a quietly recent invention — and a quietly costly one.
• meaningEvery wisdom tradition on Earth ritualised food: blessings, fasts, feast days, the gratitude said before eating. None of it was random.

For the curious eater

The most useful, durable insight in modern nutrition fits on a postcard. Michael Pollan wrote it: Eat food. Not too much. Mostly plants. The translation is shorter than any diet book.

• eat foodEat things your great-grandmother would recognise as food — not formulations of substances derived from food. That is the entire NOVA classification in one sentence.
• not too muchNo need to count calories if your food is real and you’re paying attention to hunger. Ultra-processed food short-circuits your fullness signals; real food doesn’t.
• mostly plantsThe strongest dietary signal across nearly every long-term outcome is the variety and quantity of plants. Thirty different plants a week beats any macronutrient ratio.
• — and a fifthWith people, slowly, when you’re actually hungry. Pollan didn’t write that line. Every tradition in Part 3 did.

For the scientist

The mechanisms behind why “eat real food, mostly plants, in good company” works are now reasonably well understood. Each of these is a live, peer-reviewed research field — not folklore.

• the microbiomeGut bacteria ferment dietary fibre into short-chain fatty acids (butyrate, propionate, acetate) that nourish the gut lining, regulate inflammation, modulate appetite, and signal the brain. Diversity tracks metabolic health; a depleted, monoculture microbiome tracks obesity, autoimmunity, and depression.
• the food–mood axisThe SMILES trial — an RCT in adults with moderate-to-severe depression — found a 12-week Mediterranean-style diet beat a social-support control, with about a third of the diet group reaching remission. Diet is a real, modifiable lever, not a replacement for care.
• the UPF signalIn Kevin Hall’s NIH metabolic-ward trial, the same people ate ~500 calories more per day on an ultra-processed diet than on an unprocessed one matched for sugar, fat, fibre and sodium — and gained weight in two weeks. Same macros, different form.
• the Mediterranean RCTPREDIMED — 7,000 people — showed a Mediterranean diet with extra-virgin olive oil or nuts cut major cardiovascular events by ~30% versus a low-fat control.
• fermented foodsIn a Stanford trial, ten weeks of six daily servings of fermented foods raised microbial diversity and lowered nineteen inflammatory markers — outcomes a high-fibre arm did not match.
• autophagyGo ~12+ hours without food and cells begin autophagy — clearing damaged proteins and organelles. Part of why almost every tradition independently invented fasting.

The more carefully modern science looks at how food works, the more it ends up describing what humans were already doing in the first kitchen.

What the ancients taught

Every major civilisation developed a food system — not as “alternative medicine,” but as thousands of years of empirical observation that modern nutrition is now partially confirming. Three are worth knowing well.

Ayurveda

• the six tastesSweet, sour, salty, pungent, bitter, astringent — ideally all present in each meal. Each does specific work; the practical effect is dietary diversity and balance, exactly what microbiome science would prescribe.
• the three doshasVata, pitta, kapha — constitutional types calling for different foods. The framework isn’t RCT-validated, but its intuition — the same food can heal one person and inflame another — is more accurate than one-size-fits-all guidelines. ZOE has confirmed huge variation in glucose response to identical meals.
• agniYour digestive fire. Ayurveda’s preoccupation with how you eat — warm food, sitting down, no ice water mid-meal, eating only when hungry — is a 5,000-year-old protocol for protecting digestion that mostly lines up with what gastroenterologists now advise.
• sattva · rajas · tamasFoods carry qualities that influence the mind: fresh and light → clarity; spicy and stimulating → restlessness; heavy, fried, leftover → dullness. You needn’t accept the metaphysics to notice the categories track something real.

The Mediterranean tradition

Not a “diet” so much as a way of life — olive oil as the primary fat, plenty of vegetables, legumes and whole grains, modest fish, very little red meat, fruit for dessert, wine in moderation with food, and long, communal meals. Every component has now been validated by trials: olive oil and nuts (PREDIMED), the overall pattern (Lyon Diet Heart, dementia studies), and even the social structure of the meals.

East Asian traditions

• TCMTraditional Chinese Medicine categorises foods by qi, yin/yang, and the five elements, encouraging seasonal and energetic balance. Like Ayurveda, the diagnostic frame isn’t RCT-validated; the dietary intuitions are largely sound.
• washokuTraditional Japanese cuisine: fermented foods (miso, natto, pickles) at almost every meal, small portions of many dishes, and hara hachi bu — stop at 80% full — practised especially in Okinawa, an original Blue Zone.
• fermentationKimchi, miso, doenjang, natto, tempeh — now one of the most validated dietary interventions for microbiome health.

The Blue Zones

Okinawa, Sardinia, Nicoya, Ikaria, Loma Linda — the places where people most reliably live to 100 in good health — share strikingly similar food patterns despite different continents: mostly plants, beans every day, modest portions, wine or coffee with company, lots of walking, and meals as a social act. The dietary differences are smaller than the contextual similarities: community, purpose, ritual, slowness.

What every tradition agrees on

• Eat real, seasonal, locally adapted food — mostly plants, lots of variety
• Eat warm and cooked, more often than not — protect digestion
• Eat with people. Slowly. With attention
• Bless the food, or at least pause before it — a second of awareness changes the meal
• Stop before you are stuffed — fullness should be a signal, not a stupor
• Fast, periodically — every tradition prescribed it
• Use spices and herbs as medicine — apothecaries long before flavourings
• Food is sacred — however you mean that word

Derived independently across millennia, validated point by point by twenty-first-century research — that list is more or less the answer.

The two opposite failure modes

This article is dangerous if read in only one direction. There are two ways your relationship with food can become harmful — and they look like opposites.

The ultra-processed default

Most people in the modern world drift here without ever choosing it. The signs:

• More than half your calories come from things in packets and wrappers
• You can’t recall the last vegetable you cooked from raw
• You eat alone and in a hurry most days
• You’re often vaguely tired, vaguely bloated, vaguely down, with no diagnosis
• Coffee and sugar are your scaffolding for the day

The push here is exactly what the rest of this article is about: cook more, eat plants, eat fermented foods, eat with people, slow down.

The orthorexic spiral

This is the failure mode the wellness industry will not warn you about. Orthorexia — an obsessive fixation on eating “clean” or “right” — is itself a disorder. It hides inside the language of health. The signs:

• Rising anxiety around food choices and ingredients
• Avoiding social meals because the food “isn’t clean enough”
• A list of forbidden foods that keeps growing
• Pride in restriction; guilt when restriction breaks
• Moral language attached to food — food is “good” or “bad,” and so are you
• Hours a day reading about food, supplements, protocols
• Weight loss, missed periods, fatigue, hair loss

What your doctor won’t bring up

Between those two failure modes is the population this article is really for: people doing okay, but not great, whose food is part of the picture and whose doctors won’t raise it. Things to actually ask for:

• vitamin DEspecially if you live above ~40° latitude, work indoors, or have darker skin. Subclinical deficiency is widespread and silently affects mood, immunity, and bone health.
• B12Especially if you’re vegetarian or vegan, over 50, on metformin or acid-reducers (PPIs), or constantly tired.
• iron / ferritinIron deficiency without anaemia is one of the most under-diagnosed causes of fatigue, brain fog, and restless legs — especially in menstruating women.
• omega-3 indexWhere available: the cheapest, most evidence-supported supplement most people aren’t taking.
• the real questionNot “are you eating healthy?” but “what does a typical day of eating actually look like?” Bring a three-day food log; many doctors engage seriously with data.
• a dietitianA referral to a registered dietitian — not a “nutritionist” influencer — ideally one who works in your cultural context.

Movement is part of food

The previous articles in this series — on ankylosing spondylitis and on diabetes — both made the case that movement is medicine. It applies here too, in one specific way that’s easy to act on today: a 15-minute walk after meals.

It improves digestion, blunts post-meal glucose spikes, supports the gut–brain axis, and — if you do it with the person you ate with — is one of the simplest restorations of the slow, communal eating our biology is built for. You can think of the post-meal walk as the digestive ritual every traditional culture had built into life, before cars and screens.

Cook something simple, eat it slowly, then walk it off with someone you love. None of that appears in a clinical guideline. All of it is medicine.

— the cheapest prescription in this article

The fasting question

Every civilisation invented it

Ramadan — a month of dawn-to-dusk fasting for ~1.5 billion Muslims. Lent — forty days of restriction in Christianity. Yom Kippur — the high holy fast of Judaism. Ekadashi — twice-monthly fasts in Hinduism. The Bahá’í fast, the Buddhist cut-off after noon, the Indigenous vision-quest fast. They cannot all have been arbitrary. For two decades, researchers — Valter Longo, Mark Mattson, Satchin Panda — have studied intermittent fasting with rising rigour, and found a remarkable match for what the traditions taught.

What the science shows

• time-restricted eatingLimiting eating to an 8–12 hour window improves insulin sensitivity, lipids, and inflammatory markers in many studies — especially when the window aligns with daylight.
• Ramadan fastingStudied extensively, associated with improved metabolic markers, reduced inflammation, modulation of longevity pathways (mTOR, AMPK, autophagy), and better cardiometabolic risk.
• autophagyCellular self-cleaning — the discovery that won Yoshinori Ohsumi the 2016 Nobel — kicks in around 12–16 hours into a fast. Religious traditions inadvertently engineered population-scale autophagy practice.
• the fasting-mimicking dietLongo’s FMD and alternate-day fasting show benefits in metabolic disease, with growing interest in cancer adjunct therapy and cognitive health.

The four-legged table

The diabetes article used a four-legged stool. Food deserves a table — the thing you gather around. Four legs, and a table missing one is just a board on the floor.

• what you eatMostly plants, lots of variety (~30 a week), fermented foods regularly, real fats (olive oil, nuts, seeds, fatty fish), good proteins, minimal ultra-processed food. Spices and herbs as daily medicine. Cook more than you order.
• how you eatSlowly. Sitting down. With people. With attention. With gratitude — however you mean that word. Stop before you’re stuffed.
• when you eatIn daylight when possible, with reasonable gaps between meals. Your gut likes rest as much as your body does. The traditional ~12-hour overnight fast is a freebie.
• why you eatNot just to fill yourself, but to nourish, to remember, to belong, to celebrate. Eating is one of the densest acts of meaning in a human life; treating it as a chore is a kind of impoverishment.

Underneath the four legs: self-knowledge and self-kindness. What works for your body is not necessarily what works for someone else’s, and an experiment of curiosity is always healthier than an experiment of restriction. Pay attention. Adjust. Forgive yourself the imperfect days. Show up tomorrow.

What works for your body is not necessarily what works for someone else’s. An experiment of curiosity is always healthier than an experiment of restriction.

The mini-directory

Everything in one place. Treat influencers as hypotheses, treat the trial papers and credentialed organisations as evidence, and treat your own body’s response over weeks and months as the final word.

The oldest, most counter-cultural thing

The most counter-cultural thing you can do with food in the modern world is also the oldest: cook something simple, eat it slowly, with someone you love, and pause before the first bite to be grateful that you can.

That sentence appears in no clinical guideline. It generates revenue for no industry. It is not a “diet.” It is something deeper, and older — and by every measure modern science can apply to it, quietly healing. The gut microbes thrive on the diversity. The nervous system softens in the company. The mind, given a moment of attention, eats less and enjoys more. The body, fed real food at the right pace, stops needing to be optimised.

Eat food. Not too much. Mostly plants. With people. Slowly. With a moment of reverence. Fast a little, when your life and your tradition allow.

— the whole article, in one breath

References

1. Hall KD, et al. — Ultra-processed diets cause excess calorie intake and weight gain. Cell Metabolism. (2019)
2. Estruch R, et al. — Primary prevention of cardiovascular disease with a Mediterranean diet (PREDIMED). NEJM. (2013)
3. Jacka FN, et al. — A randomised controlled trial of dietary improvement for adults with major depression (SMILES). BMC Medicine. (2017)
4. Parletta N, et al. — A Mediterranean-style diet supplemented with fish oil and depression (HELFIMED). Nutritional Neuroscience. (2017)
5. Wastyk HC, et al. — Gut-microbiota-targeted diets modulate human immune status. Cell. (2021)
6. Caffrey D, Sonnenburg JL, Devkota S. — The human-relevant biology of fermented foods. Cell Metabolism. (2024)
7. Longo VD, et al. — Intermittent and periodic fasting, longevity and disease. Nature Aging. (2021)
8. Monteiro CA, et al. — The NOVA classification of foods by extent and purpose of processing. (2019)
9. Reynolds AN, et al. — Advice to walk after meals for glycaemic control. Diabetologia. (2016)