Ancient Greeks and Romans were obsessed with diet advice, too

National Geographic

16-05-2025

From protein-filled meals to the benefits of lentils and intermittent fasting, the Classical world had strong opinions about how to stay healthy. Ancient Roman still-life mosaic fish and vegetables, 2nd century, from a villa at Tor Marancia. Vatican Museums, Rome Photograph by Giorgio Morara / Alamy Stock Photo
Before Instagram trends and DNA-based diets, Greek and Roman physicians used diet as the primary form of healthcare. Shockingly, their advice seems both modern and remarkably sensible. Too much red meat (specifically beef) could lead to cancer, wrote the second century-CE Roman medic Galen. Those who were looking to lose weight, wrote Hippocrates, should try what we call fasting cardio: exercising on an empty stomach before eating. And chicken soup, wrote Dioscorides, the father of pharmacology, 'is very often given to those in poor health in order to set them to rights.'
'The most important thing of all,' wrote the Roman writer Celsus, 'is that everyone should be familiar with the nature of their own body.' Most people have some kind of bodily weakness, he continued—and whether or not you're inclined to gain weight or struggle to keep it on, to be constipated or to have food pass right through you— 'whichever part is the most problematic should always get the most attention,' and we should adjust our diets accordingly. 'The Banquet of Cleopatra' by Giovanni Battista Tiepolo (1696-1770). Photograph by IanDagnall Computing / Alamy Stock Photo It's all about balance
Ancient ideas about diet were grounded in archaic theories about how the body worked. Most Greek and Roman doctors believed that all bodies existed on a spectrum of hot, cold, wet, and dry. In general, from the Roman doctor Galen onwards, the properties of wet, dry, hot, and cold were believed to correspond to humors (or substances) in the body. Blood was hot and moist; phlegm was cold and moist; black bile was cold and dry; and yellow bile was hot and dry. As early as Hippocrates, it was believed that a deficiency or excess in one of these substances would lead to pain and disease. The primary ways to regulate them was through exercise, which would heat the body, and diet, which depending on the substances could either cool or heat the body from within.
Some bodies—such as those of women—were considered more predisposed to be 'wet,' while others—like young men—were hotter and dryer, but broadly speaking, health could be found by keeping these properties in balance, explains Claire Bubb, Assistant Professor of Classical Literature and Science at the Institute for the Study of the Ancient World at NYU and author of the recently published How to Eat: An Ancient Guide for Healthy Living.
'To put it fairly simplistically,' Bubb says, 'the basic theory was that a patient who was suffering from a hot and dry disease [e.g. cholera] would likely find some relief in a cool and moist diet (and it would be considerably less risky to give someone some lettuce than to give them a …drug, whose downside risk could be catastrophic).' Lettuce was seen as a cooling food that could regulate body temperature in those who were overheating, whether because of their intrinsic nature, because of disease, or because of the weather.
(Here's how drinking bone broth benefits your health)
Many of the heating and cooling properties of foodstuff feel instinctive: lettuce and cucumbers are cooling, but arugula is heating because it is peppery. Meat is a heating food, particularly if it is prepared through roasting (which does not use liquid and utilizes higher temperatures in preparation). Crudites are cooling food and thus better reserved for summer, when the body needs to be cooled down.
According to ancient medics, these prescriptions worked. Galen claimed in On the Properties of Foodstuffs that as a young man—who, on account of his age was hotter—he successfully used lettuce for its cooling properties. Now that he was older, it had taken on a new use as a sleep aid. 'The only remedy against insomnia for me,' he wrote, 'was lettuce eaten in the evening.'
While diet was important for diagnosing and treating disease, it was even more essential as a means of preventing illness. With surgical and pharmaceutical treatments in their infancy, most illnesses were incurable. As a result, diet was preventive healthcare—and one of the few ways a person could try to avoid sickness. If a person needed to be cooled down, wrote Celsus in On Medicine, they should drink cold water, sleep, and eat acidic foods. If they needed to be warmed up, they should eat 'all salty, bitter, and meaty foods.'
(The Mediterranean diet has stood the test of time for a reason) Fragment of an Italian Fresco with a Meal Preparation. Photograph by Sepia Times/Universal Images Group via Getty Images Personalized diet
Ancient dietary advice was 'extremely personalized,' says Bubb—'the ideal diet needs to be tailored to the individual, so the idea of a universal recommended daily amount would not have made sense.' An ancient athlete, a beefy gladiator for example, was advised to eat 'nourishing,' fortifying food like pork or beef. An ancient office worker stuck behind a desk all day doing bookkeeping or other bureaucratic tasks would do better with lighter food like fish. But some people, the ancient doctor Galen noted, digested beef more easily than fish. The rules would be different for them.
In general, most patients were advised to follow two key principles: eat seasonally and avoid drastic changes. The former was less about availability (in that sense everyone ate seasonally) and more about adjusting for the weather: in summer, eat light, cooling foods (cucumbers, lettuce, raw vegetables); in winter, consume a warming diet of heavier comfort foods (roasted meat and bread).
While most of these authors were partaking in what we might call the Mediterranean diet—olive oil, fish, vegetables, and grains—an ancient person's diet was conditioned by their socioeconomic status. The foundations of the 'average' diet were lentils, bread (of the denser darker kind), a fermented fish sauce known as garum, and occasional fish and, in a good week, meat. The wealthy had access to highly seasoned and prepared foodstuffs, a wide array of different kinds of meats and fish like flamingo tongue and panther.
As for drastic changes, while ancient physicians understood the desire for bodily transformation, they believed that radical shifts in diet could cause illness. Transitioning from a winter to a summer diet overnight, for example, was seen as extreme—as extreme as going from a sedentary lifestyle one week to running marathons the next. Celsus warned 'you can't go from overexertion to sudden rest, nor from extended rest straight to exertion without seriously bad effects.' Even when switching from season to season and increasing exercise, wrote Diocles, in his Regimen for Health, you should 'ramp it up slowly and be cautious of overdoing it.' Interestingly, modern studies agree with what the ancients believed: small, incremental lifestyle changes are much more effective and sustainable for improving overall health than large, abrupt ones.
(Fish guts were the ketchup of ancient Rome)
While modern doctors debate the nutritional value of various kinds of fat (with 'good fats' like avocados and nuts being recommended, while fried foods and processed meats are tied to heart disease), ancient experts disagreed about ingredients like lentils. Lentils were valorized by Stoic philosophers like Zeno of Citium and Musonius Rufus, for whom diet was very much about self-restraint and avoiding the excesses of fancy foreign foods. In On Keeping Well, the Greek writer Plutarch argued that no one should stray too far from a simple diet of lentils because 'less expensive things are always healthier for the body.' But for many Roman doctors, Bubb said, lentils were viewed as very unhealthy. Dioscorides claimed in his Medical Substances that 'the lentil, when eaten steadily, causes dim sightedness, poor digestion, stomachache, gas…and constipation in the bowels.'
Similarly, while most people praised the merits of cabbage as a kind of miracle cure-all, others disagreed. 'Cabbage,' wrote Cato the Elder, a Roman statesman and the author of a work On Farming, 'is the vegetable that surpasses all others.' It could be eaten raw or cooked, and sprinkled with vinegar, it did 'the belly good,' even producing urine that itself had medicinal properties. Eaten before a party, he added, it could help prevent a hangover and indigestion from overeating. It not only cleansed the body but could also clear the head.
Writing three centuries later, Galen—undoubtedly the better doctor—disagreed. While he acknowledged that cabbage had cleansing properties, he wrote in On the Properties of Foodstuffs that it 'is emphatically not a wholesome food, like lettuce is, but has a pernicious and bad-smelling juice.'
(Don't ignore these protein-packed superfoods) Fasting and good fats
Some aspects of ancient dietary advice cohere surprisingly well with modern lifestyle trends and philosophies. As early as the fifth century BCE, Bubb said, Hippocratic texts advised people to try intermittent fasting (one meal a day was common), cross-training by sailing, hunting, and walking on varied terrain, and eating a high-fat diet (think butter, sheep's cheese, and olive oil) to lose weight. 'Dishes should be high in fat,' wrote Hippocrates 'so that [the dieter] feels satiated after the smallest amount.' Today scientists agree that, in a controlled environment, fat does have an effect on satiety.
Still, not all the advice seems practical—or even safe—for the health-conscious today. The comparatively limited range of medical treatments meant that Hippocratic doctors often recommended routine purging and advised wine for people of all ages (albeit watered down). Extensive time spent bathing and getting massages, prescribed as part of a general health-preserving regimen, sounds appealing—but would make it difficult to maintain modern work hours.
And then there's the quirky stuff. The ancient fixation on cabbage, which was almost a universal drug to many around the ancient Mediterranean, seems fairly innocuous. But Bubb notes that other ancient medical opinions are more dubious—such as the idea that 'rotting basil spontaneously breeds scorpions, that eating too many figs causes headlice, that fruit is generally very bad for you—or that walking around nude is a good weight loss strategy.'